docs: macro chooser generates adl_serializer for non-default-constructible types

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
docs: add figures, table captions and a macro chooser
2026-10-26 12:14:46 +00:00 · 2026-10-26 11:17:22 +01:00 · 2026-10-26 10:42:00 +01:00 · 2026-10-25 20:40:26 +01:00 · 2026-10-25 12:08:58 +01:00 · 2026-10-25 12:08:36 +01:00
691 changed files with 21440 additions and 8833 deletions
@@ -1,3 +1,33 @@
+# Style or vendor rule sets that do not fit a header-only library:
+#   altera-*, fuchsia-*, llvmlibc-*, android-cloexec-fopen, boost-use-ranges, llvm-header-guard,
+#   llvm-include-order, llvm-prefer-static-over-anonymous-namespace, llvm-use-ranges,
+#   misc-use-anonymous-namespace, google-runtime-float, google-runtime-int, hicpp-signed-bitwise,
+#   bugprone-signed-bitwise, hicpp-explicit-conversions, google-explicit-constructor,
+#   cppcoreguidelines-explicit-constructor, misc-explicit-constructor (implicit conversions are the
+#   API), readability-trailing-comma,
+#   hicpp-avoid-goto / cppcoreguidelines-avoid-goto, hicpp-no-array-decay,
+#   hicpp-uppercase-literal-suffix, readability-uppercase-literal-suffix, modernize-use-trailing-return-type.
+# Constructs the library needs on purpose (the library supports C++11 and legacy compilers):
+#   cppcoreguidelines-macro-usage, cppcoreguidelines-avoid-do-while (macros),
+#   cppcoreguidelines-pro-bounds-*, cppcoreguidelines-pro-type-reinterpret-cast,
+#   cppcoreguidelines-pro-type-union-access (parsers, serializers, basic_json's value union),
+#   cppcoreguidelines-avoid-const-or-ref-data-members, cppcoreguidelines-rvalue-reference-param-not-moved,
+#   cppcoreguidelines-avoid-non-const-global-variables, misc-non-private-member-variables-in-classes,
+#   misc-no-recursion (value walks are recursive, bounded by detail::recursion_depth_limit()),
+#   modernize-type-traits, modernize-use-constraints, modernize-use-ranges, modernize-use-std-numbers,
+#   modernize-use-designated-initializers, modernize-use-nodiscard, modernize-concat-nested-namespaces,
+#   readability-redundant-typename, readability-redundant-parentheses,
+#   readability-redundant-access-specifiers, readability-simplify-boolean-expr,
+#   readability-use-concise-preprocessor-directives, modernize-use-string-view,
+#   modernize-use-integer-sign-comparison (needs std::cmp_less; the flagged
+#   static_cast<std::size_t>(end - pos) < n comparisons are deliberate)
+#   (all need a newer standard or compiler than C++11, or would change macro-generated or
+#   deliberately explicit code).
+# Too noisy to be useful (numeric parsing/formatting code, doctest, tests):
+#   bugprone-easily-swappable-parameters, cppcoreguidelines-avoid-magic-numbers, readability-magic-numbers,
+#   readability-identifier-length, readability-function-cognitive-complexity, performance-enum-size,
+#   concurrency-mt-unsafe, misc-confusable-identifiers, misc-include-cleaner (run on its own for
+#   the consumer headers in cmake/ci.cmake).
 # portability-avoid-pragma-once: kept disabled on purpose. #pragma once is accepted
 # by every supported compiler, and tools/amalgamate/amalgamate.py strips it from
 # single_include, so there is nothing left to fix here.
@@ -10,14 +40,14 @@ Checks: '*,
         -android-cloexec-fopen,
         -boost-use-ranges,
         -bugprone-easily-swappable-parameters,
-         -cert-err58-cpp,
-         -clang-analyzer-webkit.NoUncountedMemberChecker,
+         -bugprone-signed-bitwise,
         -concurrency-mt-unsafe,
         -cppcoreguidelines-avoid-const-or-ref-data-members,
         -cppcoreguidelines-avoid-do-while,
         -cppcoreguidelines-avoid-goto,
         -cppcoreguidelines-avoid-magic-numbers,
         -cppcoreguidelines-avoid-non-const-global-variables,
+         -cppcoreguidelines-explicit-constructor,
         -cppcoreguidelines-macro-usage,
         -cppcoreguidelines-pro-bounds-avoid-unchecked-container-access,
         -cppcoreguidelines-pro-bounds-array-to-pointer-decay,
@@ -26,19 +56,15 @@ Checks: '*,
         -cppcoreguidelines-pro-type-reinterpret-cast,
         -cppcoreguidelines-pro-type-union-access,
         -cppcoreguidelines-rvalue-reference-param-not-moved,
-         -cppcoreguidelines-virtual-class-destructor,
         -fuchsia-default-arguments-calls,
         -fuchsia-default-arguments-declarations,
         -fuchsia-overloaded-operator,
         -google-explicit-constructor,
-         -google-readability-function-size,
         -google-runtime-float,
         -google-runtime-int,
         -hicpp-avoid-goto,
         -hicpp-explicit-conversions,
-         -hicpp-function-size,
         -hicpp-no-array-decay,
-         -hicpp-no-assembler,
         -hicpp-signed-bitwise,
         -hicpp-uppercase-literal-suffix,
         -llvm-header-guard,
@@ -48,6 +74,7 @@ Checks: '*,
         -llvmlibc-*,
         -misc-use-anonymous-namespace,
         -misc-confusable-identifiers,
+         -misc-explicit-constructor,
         -misc-include-cleaner,
         -misc-no-recursion,
         -misc-non-private-member-variables-in-classes,
@@ -55,20 +82,22 @@ Checks: '*,
         -modernize-type-traits,
         -modernize-use-constraints,
         -modernize-use-designated-initializers,
+         -modernize-use-integer-sign-comparison,
         -modernize-use-nodiscard,
         -modernize-use-ranges,
+         -modernize-use-string-view,
         -modernize-use-std-numbers,
         -modernize-use-trailing-return-type,
         -performance-enum-size,
         -portability-avoid-pragma-once,
         -readability-function-cognitive-complexity,
-         -readability-function-size,
         -readability-identifier-length,
         -readability-magic-numbers,
         -readability-redundant-access-specifiers,
         -readability-redundant-parentheses,
         -readability-redundant-typename,
         -readability-simplify-boolean-expr,
+         -readability-trailing-comma,
         -readability-uppercase-literal-suffix,
         -readability-use-concise-preprocessor-directives'

@@ -29,13 +29,6 @@ updates:
      - dependency-name: mermaid
        update-types: ["version-update:semver-major"]

-  - package-ecosystem: pip
-    directory: /.github/requirements
-    schedule:
-      interval: daily
-    cooldown:
-      default-days: 7
-
  - package-ecosystem: pip
    directory: /tools/astyle
    schedule:
@@ -43,7 +36,7 @@ updates:
    cooldown:
      default-days: 7
    ignore:
-      # astyle is deliberately pinned (see tools/astyle/requirements.in): newer versions
+      # astyle is deliberately pinned (see tools/astyle/requirements.txt): newer versions
      # reformat the code, and the pinned version defines the formatting CI enforces
      - dependency-name: astyle

@@ -1 +0,0 @@
-meson==1.12.1
@@ -1,10 +0,0 @@
-#
-# This file is autogenerated by pip-compile with Python 3.14
-# by the following command:
-#
-#    pip-compile --generate-hashes --no-emit-index-url --output-file=.github/requirements/meson.txt --strip-extras .github/requirements/meson.in
-#
-meson==1.12.1 \
-    --hash=sha256:930bc7542cbd9f57009e182fd014eba48cf1a0180a7b9006d2d32d8f168d8b02 \
-    --hash=sha256:ab0a6ca09f8ef70c564c8241fb5a23957886a0b53fb58412b5e07eaf07dba743
-    # via -r .github/requirements/meson.in
@@ -1 +0,0 @@
-semgrep==1.182.1
@@ -67,10 +67,10 @@ jobs:
      - name: Install astyle
        run: |
          python3 -mvenv venv
-          venv/bin/pip3 install --require-hashes -r $MAIN_DIR/tools/astyle/requirements.txt
+          venv/bin/pip3 install -r $MAIN_DIR/tools/astyle/requirements.txt

      - name: Install generate_natvis dependencies
-        run: pip3 install --require-hashes -r $MAIN_DIR/tools/generate_natvis/requirements.txt
+        run: pip3 install -r $NATVIS_TOOL_DIR/requirements.txt

      - name: Regenerate the tools/macro_builder tables in macro_scope.hpp
        run: |
@@ -31,12 +31,3 @@ jobs:
          persist-credentials: false
      - name: 'Dependency Review'
        uses: actions/dependency-review-action@a1d282b36b6f3519aa1f3fc636f609c47dddb294 # v5.0.0
-        with:
-          # Semgrep pins mcp==1.29.0 and opentelemetry-api~=1.37.0 exactly
-          # (.github/requirements/semgrep.txt), so these cannot be upgraded
-          # until Semgrep lifts its pins. They do not apply to our use: CI
-          # only runs `semgrep scan` on the checkout and never starts the MCP
-          # server (GHSA-84m7-p3x7-pcfv, StreamableHTTP sessions) or parses
-          # incoming trace context (GHSA-xcq7-p3pf-p88h, tracestate parsing).
-          # Remove the entries once a Semgrep release allows the fixed versions.
-          allow-ghsas: GHSA-84m7-p3x7-pcfv, GHSA-xcq7-p3pf-p88h
@@ -43,7 +43,8 @@ jobs:
      - name: flawfinder_scan
        uses: david-a-wheeler/flawfinder@c4216b74cf2639ffa98503768bd6e4299b5440c9 # v2.0.20
        with:
-          arguments: '--sarif ./'
+          # single_include/ is omitted: it is generated from include/ and would report every finding twice
+          arguments: '--sarif ./cmake ./docs ./include ./src ./tests ./tools'
          output: 'flawfinder_results.sarif'

      - name: Upload analysis results to GitHub Security tab
@@ -53,7 +53,7 @@ jobs:
      # SEMGREP_APP_TOKEN is still passed through so registry auth works if a
      # token is ever added.
      - name: Install Semgrep
-        run: python3 -m pip install --user --require-hashes -r .github/requirements/semgrep.txt
+        run: python3 -m pip install --user semgrep==1.168.0

      # `semgrep scan --sarif` always exits 0 even with findings; continue-on-error
      # is a safety net so the SARIF upload still runs if the scan itself errors.
@@ -42,7 +42,7 @@ jobs:
      - name: Check that Meson and pkg-config offer the CMake options
        run: make check_build_options
      - name: Install Meson
-        run: pip install --require-hashes -r .github/requirements/meson.txt
+        run: pip install meson
      - name: Install with Meson
        run: |
          meson setup build-meson --prefix=${{ github.workspace }}/install
@@ -151,7 +151,7 @@ The `json` class provides an API for manipulating a JSON value. To create a `jso
 ```cpp
 #include <fstream>
 #include <nlohmann/json.hpp>
-using json = nlohmann::json;
+using nlohmann::json;

 // ...

@@ -164,7 +164,7 @@ If using modules (enabled with `NLOHMANN_JSON_BUILD_MODULES`), this example beco
 import std;
 import nlohmann.json;

-using json = nlohmann::json;
+using nlohmann::json;

 // ...

@@ -842,7 +842,7 @@ assert(p == p2);
 To make this work with one of your types, you only need to provide two functions:

 ```cpp
-using json = nlohmann::json;
+using nlohmann::json;

 namespace ns {
    void to_json(json& j, const person& p) {
@@ -1257,7 +1257,7 @@ See the page [quality assurance](https://json.nlohmann.me/community/quality_assu
 #include <nlohmann/json.hpp>

 // for convenience
-using json = nlohmann::json;
+using nlohmann::json;
 ```

 to the files you want to process JSON and set the necessary switches to enable C++11 (e.g., `-std=c++11` for GCC and Clang).
@@ -341,13 +341,14 @@ def download(url, docs) -> str:
        raise ValueError(f'not an http(s) URL: {url}')
    req = urllib.request.Request(u.geturl(), headers={'User-Agent': USER_AGENT})
    # (the scheme is checked above)
+    # nosemgrep: python.lang.security.audit.dynamic-urllib-use-detected.dynamic-urllib-use-detected
    with urllib.request.urlopen(req, timeout=20) as r:  # nosec B310
        data = r.read()
        ctype = r.headers.get_content_type()
    path = urllib.parse.unquote(u.path).lstrip('/')
    ext = os.path.splitext(path)[1]
    if u.query or not ext or path.endswith('/'):
-        digest = hashlib.sha1(url.encode(), usedforsecurity=False).hexdigest()[:12]
+        digest = hashlib.sha256(url.encode()).hexdigest()[:12]
        path = os.path.join(os.path.dirname(path), digest + CONTENT_TYPE_EXT.get(ctype, ext or '.bin'))
    rel = os.path.normpath(os.path.join('assets', 'external', u.hostname, path))
    out = os.path.join(docs, rel)
@@ -30,6 +30,14 @@ struct adl_serializer {
 - [**from_json**](from_json.md) - convert a JSON value to any value type
 - [**to_json**](to_json.md) - convert any value type to a JSON value

+## See also
+
+- [Arbitrary type conversions](../../features/arbitrary_types.md) - how to make your types convertible
+- [**get**](../basic_json/get.md) / [**get_to**](../basic_json/get_to.md) - convert a JSON value to a C++ type
+- [**basic_json**](../basic_json/basic_json.md) - construct a JSON value from a C++ value
+- [**NLOHMANN_DEFINE_TYPE_INTRUSIVE**](../macros/nlohmann_define_type_intrusive.md) - generate the conversion functions for a type
+- [Specializing enum conversion](../../features/enum_conversion.md)
+
 ## Version history

 - Added in version 2.1.0.
@@ -23,6 +23,9 @@ Checks whether the input is valid JSON.
    respectively as UTF-8, UTF-16, and UTF-32. If `SentinelType` differs from `IteratorType`, it must be comparable to
    the iterator type with `operator!=`.
    
+    Ill-formed UTF-16 and UTF-32 sequences are rejected: a lone surrogate, a high surrogate that is not followed by its
+    low surrogate, and a code point above `U+10FFFF` all make this function return `false`.
+
 Unlike the [`parse()`](parse.md) function, this function neither throws an exception in case of invalid JSON input
 (i.e., a parse error) nor creates diagnostic information.

@@ -35,9 +38,12 @@ Unlike the [`parse()`](parse.md) function, this function neither throws an excep
    - a `#!c FILE` pointer (throws if null)
    - a C-style array of characters
    - a pointer to a null-terminated string of single byte characters (throws if null)
-    - a `std::string`
+    - a `std::string` or a `std::string_view` (C++17)
    - a container `obj` for which `begin(obj)` and `end(obj)` produce a valid pair of iterators
      (as found via ADL or member functions, with semantics compatible to `std::begin` and `std::end`)
+    - wide characters (`wchar_t`, `char16_t`, `char32_t`), which are converted to UTF-8: a wide string object
+      (`std::wstring`, `std::u16string`, `std::u32string`) or an array (e.g. a wide string literal); a pointer to a
+      null-terminated wide string (e.g. `std::u16string::c_str()`) is not supported

 `IteratorType`
 :   a compatible iterator type, for instance.
@@ -125,6 +131,21 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
    --8<-- "examples/accept__iterator_pair.output"
    ```

+??? example "Example: (3) reading from UTF-16 strings"
+
+    The encoding is deduced from the character type of the input. String literals like `u"..."`, `U"..."`, and
+    `L"..."` work as well.
+
+    ```cpp
+    --8<-- "examples/accept__wide_string.cpp"
+    ```
+
+    Output:
+
+    ```json
+    --8<-- "examples/accept__wide_string.output"
+    ```
+
 ## See also

 - [parse](parse.md) - deserialize from a compatible input
@@ -151,6 +172,9 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
  ([`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md)).
 - Parsing from a `FILE*` locks the file once instead of once per character in version 3.13.0
  ([`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md)).
+- Ill-formed UTF-16 and UTF-32 input (a lone surrogate, a high surrogate that is not followed by its low surrogate, or
+  a code point above `U+10FFFF`) is rejected in version 3.13.0; before that, some such sequences were accepted or
+  ended the input silently.

 !!! warning "Deprecation"

@@ -239,9 +239,8 @@ Strong exception safety: if an exception occurs, the original value stays intact

 1. Added in version 1.0.0.
 2. Added in version 1.0.0.
-3. Added in version 3.11.0. Fixed in version 3.13.0 to consistently accept `std::string_view`-convertible keys, as
-   already supported by [`operator[]`](operator[].md), [`value`](value.md), [`find`](find.md), and other lookup
-   functions.
+3. Added in version 3.11.0. Support for keys convertible to `std::string_view` added in version 3.13.0, consistently
+   across the lookup functions.
 4. Added in version 2.0.0. Throws [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109) instead of
 [`out_of_range.404`](../../home/exceptions.md#jsonexceptionout_of_range404) for a one-character array index that is not
 a digit (e.g., `/x`) in version 3.13.0, as it already did for longer ones.
@@ -63,4 +63,4 @@ Constant.
 ## Version history

 - Added in version 1.0.0.
- Adjusted code to return reference to binary values in version 3.8.0.
+- Binary values are supported since version 3.8.0.
@@ -113,19 +113,22 @@ basic_json(basic_json&& other) noexcept;

    ```mermaid
    flowchart TD
-        A(["initializer_list init"]) --> B{"empty, or every element is a 2-element<br/>array whose first element is a string?"}
-        B -->|"yes"| C{"type_deduction"}
-        B -->|"no"| D{"type_deduction"}
+        A(["initializer_list init"]) --> B{{"empty, or every element is a 2-element<br/>array whose first element is a string?"}}
+        B -->|"yes"| C{{"type_deduction"}}
+        B -->|"no"| D{{"type_deduction"}}
        C -->|"true"| OBJ["create object"]
-        C -->|"false"| E{"manual_type"}
+        C -->|"false"| E{{"manual_type"}}
        E -->|"object"| OBJ
        E -->|"array"| ARR["create array"]
        D -->|"true"| ARR
-        D -->|"false"| F{"manual_type"}
+        D -->|"false"| F{{"manual_type"}}
        F -->|"array"| ARR
        F -->|"object"| ERR["throw type_error.301"]
    ```

+    <p class="nj-caption" markdown>Decision flow for an initializer list: hexagons are checks, edge labels are their
+    outcomes, and rectangles are the resulting value or exception.</p>
+
    The rules aim to create the best fit between a C++ initializer list and JSON values. The rationale is as follows:
    
    1. The empty initializer list is written as `#!cpp {}` which is exactly an empty JSON object.
@@ -482,15 +485,15 @@ basic_json(basic_json&& other) noexcept;

 ## Version history

-1. Since version 1.0.0.
-2. Since version 1.0.0.
-3. Since version 2.1.0.
-4. Since version 3.2.0. Explicit for different string types if `JSON_USE_IMPLICIT_CONVERSIONS` is `0` since
+1. Added in version 1.0.0.
+2. Added in version 1.0.0.
+3. Added in version 2.1.0.
+4. Added in version 3.1.2. Explicit for different string types if `JSON_USE_IMPLICIT_CONVERSIONS` is `0` since
   version 3.13.0.
-5. Since version 1.0.0.
-6. Since version 1.0.0.
-7. Since version 1.0.0. Fixed in version 3.13.0 to also check the iterator range for binary values; before, a range
+5. Added in version 1.0.0.
+6. Added in version 1.0.0.
+7. Added in version 1.0.0. Fixed in version 3.13.0 to also check the iterator range for binary values; before, a range
   that did not cover the whole value (such as `(end(), end())`) was accepted and the whole binary value was copied,
   unlike the other primitive types.
-8. Since version 1.0.0.
-9. Since version 1.0.0.
+8. Added in version 1.0.0.
+9. Added in version 1.0.0.
@@ -7,7 +7,12 @@ const_iterator begin() const noexcept;

 Returns an iterator to the first element.

-![Illustration from cppreference.com](../../images/range-begin-end.svg)
+<div class="nj-fig-wrap" markdown>
+--8<-- "images/range-begin-end.svg"
+</div>
+
+<p class="nj-caption" markdown>`begin()` points to the first element and `end()` to the position after the last element;
+the dashed cell is the past-the-last position, which must not be dereferenced.</p>

 ## Return value

@@ -6,7 +6,12 @@ const_iterator cbegin() const noexcept;

 Returns an iterator to the first element.

-![Illustration from cppreference.com](../../images/range-begin-end.svg)
+<div class="nj-fig-wrap" markdown>
+--8<-- "images/range-begin-end.svg"
+</div>
+
+<p class="nj-caption" markdown>`cbegin()` points to the first element, like `begin()`, and `end()` to the position after
+the last element; the dashed cell is the past-the-last position, which must not be dereferenced.</p>

 ## Return value

@@ -6,7 +6,12 @@ const_iterator cend() const noexcept;

 Returns an iterator to one past the last element.

-![Illustration from cppreference.com](../../images/range-begin-end.svg)
+<div class="nj-fig-wrap" markdown>
+--8<-- "images/range-begin-end.svg"
+</div>
+
+<p class="nj-caption" markdown>`cend()` points to the position after the last element, like `end()`, and `begin()` to
+the first element; the dashed cell is the past-the-last position, which must not be dereferenced.</p>

 ## Return value

@@ -141,9 +141,8 @@ Logarithmic in the size of the JSON object.
 ## Version history

 1. Added in version 3.11.0.
-2. Added in version 3.6.0. Extended template `KeyType` to support comparable types in version 3.11.0. Fixed in
-   version 3.13.0 to consistently accept `std::string_view`-convertible keys, as already supported by
-   [`operator[]`](operator[].md), [`at`](at.md), [`value`](value.md), and other lookup functions.
+2. Added in version 3.6.0. Extended template `KeyType` to support comparable types in version 3.11.0. Support for keys
+   convertible to `std::string_view` added in version 3.13.0, consistently across the lookup functions.
 3. Added in version 3.7.0.
 4. Deleted overloads for integral key types added in version 3.13.0 to reject such calls at compile time instead of
   causing undefined behavior at runtime.
@@ -92,8 +92,7 @@ Logarithmic in the size of the JSON object.
 ## Version history

 1. Added in version 3.11.0.
-2. Added in version 1.0.0. Changed parameter `key` type to `KeyType&&` in version 3.11.0. Fixed in version 3.13.0 to
-   consistently accept `std::string_view`-convertible keys, as already supported by [`operator[]`](operator[].md),
-   [`at`](at.md), [`value`](value.md), and other lookup functions.
+2. Added in version 1.0.0. Changed to support comparable key types in version 3.11.0. Support for keys convertible to
+   `std::string_view` added in version 3.13.0, consistently across the lookup functions.
 3. Deleted overload for integral key types added in version 3.13.0 to reject such calls at compile time instead of
   causing undefined behavior at runtime.
@@ -6,7 +6,13 @@ const_reverse_iterator crbegin() const noexcept;

 Returns an iterator to the reverse-beginning; that is, the last element.

-![Illustration from cppreference.com](../../images/range-rbegin-rend.svg)
+<div class="nj-fig-wrap" markdown>
+--8<-- "images/range-rbegin-rend.svg"
+</div>
+
+<p class="nj-caption" markdown>`crbegin()` points to the last element, like `rbegin()`, and `rend()` to the position
+before the first element. The upper row is the reversed sequence and the lower row the forward sequence; dashed arrows
+link each reverse iterator to the forward iterator it stores, and dashed cells are past-the-last positions.</p>

 ## Return value

@@ -7,7 +7,13 @@ const_reverse_iterator crend() const noexcept;
 Returns an iterator to the reverse-end; that is, one before the first element. This element acts as a placeholder,
 attempting to access it results in undefined behavior.

-![Illustration from cppreference.com](../../images/range-rbegin-rend.svg)
+<div class="nj-fig-wrap" markdown>
+--8<-- "images/range-rbegin-rend.svg"
+</div>
+
+<p class="nj-caption" markdown>`crend()` points to the position before the first element, like `rend()`, and `rbegin()`
+to the last element. The upper row is the reversed sequence and the lower row the forward sequence; dashed arrows link
+each reverse iterator to the forward iterator it stores, and dashed cells are past-the-last positions.</p>

 ## Return value

@@ -69,6 +69,6 @@ Logarithmic in the size of the container, O(log(`size()`)).

 ## Version history

- Since version 2.0.8.
+- Added in version 2.0.8.
 - Fixed in version 3.13.0: for [`ordered_json`](../ordered_json.md), the value could previously only be passed as an
  rvalue; it can now also be passed as an lvalue or a `#!cpp const` lvalue, matching the behavior of `json`.
@@ -67,5 +67,5 @@ Amortized constant.

 ## Version history

- Since version 2.0.8.
+- Added in version 2.0.8.
 - Returns reference since 3.7.0.
@@ -7,7 +7,12 @@ const_iterator end() const noexcept;

 Returns an iterator to one past the last element.

-![Illustration from cppreference.com](../../images/range-begin-end.svg)
+<div class="nj-fig-wrap" markdown>
+--8<-- "images/range-begin-end.svg"
+</div>
+
+<p class="nj-caption" markdown>`end()` points to the position after the last element and `begin()` to the first element;
+the dashed cell is the past-the-last position, which must not be dereferenced.</p>

 ## Return value

@@ -213,7 +213,6 @@ Strong exception safety: if an exception occurs, the original value stays intact
 1. Added in version 1.0.0. Added support for binary types in version 3.8.0.
 2. Added in version 1.0.0. Added support for binary types in version 3.8.0.
 3. Added in version 1.0.0.
-4. Added in version 3.11.0. Fixed in version 3.13.0 to consistently accept `std::string_view`-convertible keys, as
-   already supported by [`operator[]`](operator[].md), [`at`](at.md), [`value`](value.md), and other lookup
-   functions.
+4. Added in version 3.11.0. Support for keys convertible to `std::string_view` added in version 3.13.0, consistently
+   across the lookup functions.
 5. Added in version 1.0.0.
@@ -40,6 +40,9 @@ classDiagram
    style json_exception fill:#CCCCFF
 ```

+<p class="nj-caption" markdown>Class hierarchy of the library's exceptions; arrows point from a derived class to its
+base class, and the highlighted box is `basic_json::exception`.</p>
+
 Subclasses:

 - [`parse_error`](parse_error.md) for exceptions indicating a parse error
@@ -84,4 +87,4 @@ constructor.

 ## Version history

- Since version 3.0.0.
+- Added in version 3.0.0.
@@ -99,8 +99,7 @@ Logarithmic in the size of the JSON object.
 ## Version history

 1. Added in version 3.11.0.
-2. Added in version 1.0.0. Changed to support comparable types in version 3.11.0. Fixed in version 3.13.0 to
-   consistently accept `std::string_view`-convertible keys, as already supported by [`operator[]`](operator[].md),
-   [`at`](at.md), [`value`](value.md), and other lookup functions.
+2. Added in version 1.0.0. Changed to support comparable types in version 3.11.0. Support for keys convertible to
+   `std::string_view` added in version 3.13.0, consistently across the lookup functions.
 3. Deleted overloads for integral key types added in version 3.13.0 to reject such calls at compile time instead of
   causing undefined behavior at runtime.
@@ -57,4 +57,4 @@ Constant.
 ## Version history

 - Added in version 1.0.0.
- Adjusted code to return reference to binary values in version 3.8.0.
+- Binary values are supported since version 3.8.0.
@@ -188,6 +188,6 @@ overload (3).

 ## Version history

-1. Since version 2.1.0.
-2. Since version 2.1.0. Extended to work with other specializations of `basic_json` in version 3.2.0.
-3. Since version 1.0.0.
+1. Added in version 2.1.0.
+2. Added in version 2.1.0. Extended to work with other specializations of `basic_json` in version 3.1.2.
+3. Added in version 1.0.0.
@@ -45,7 +45,7 @@ Constant.
    #include <iostream>
    #include <nlohmann/json.hpp>
    
-    using json = nlohmann::json;
+    using nlohmann::json;
    
    int main()
    {
@@ -76,5 +76,5 @@ Depends on the `json_serializer<ValueType>::from_json()` implementation.

 ## Version history

- Since version 3.3.0.
+- Added in version 3.3.0.
 - Added a `static_assert` with a clear message for `const` arguments in version 3.13.0.
@@ -44,6 +44,22 @@ are collected in [Template Parameter Requirements](../../features/types/template
 - [**json**](../json.md) - default specialization
 - [**ordered_json**](../ordered_json.md) - a specialization that maintains the insertion order of object keys

+## Documents and views
+
+Besides `basic_json`, the library offers a second way to hold a parsed JSON text: a
+[`basic_json_document`](../basic_json_document/index.md), which owns or borrows the text and holds a flat index of the
+values in it, and a [`basic_json_view`](../basic_json_view/index.md), a read-only handle to one value of such a document.
+Both are defined in the header `<nlohmann/json_view.hpp>`; see
+[Zero-copy JSON views](../../features/json_view.md) for the concept and the trade-offs.
+
+- [**json_document**](../json_document.md) / [**ordered_json_document**](../ordered_json_document.md) - read-only
+  documents of the `basic_json` specialization they belong to
+- [**json_editable_document**](../json_editable_document.md) /
+  [**ordered_json_editable_document**](../ordered_json_editable_document.md) - documents that can be modified in place
+- [**json_view**](../json_view.md) / [**ordered_json_view**](../ordered_json_view.md) - views of a document
+- [**json_editable_view**](../json_editable_view.md) /
+  [**ordered_json_editable_view**](../ordered_json_editable_view.md) - views of an editable document
+
 ## Iterator invalidation

 All operations that add values to an **array** ([`push_back`](push_back.md) , [`operator+=`](operator+=.md),
@@ -343,6 +359,9 @@ Access to the JSON value
 ## See also

 - [RFC 8259: The JavaScript Object Notation (JSON) Data Interchange Format](https://tools.ietf.org/html/rfc8259)
+- [basic_json_document](../basic_json_document/index.md) / [basic_json_view](../basic_json_view/index.md) - parse a JSON
+  text into a flat index and read it through a view
+- [Zero-copy JSON views](../../features/json_view.md) - when to use a document and a view instead of a `basic_json`

 ## Version history

@@ -40,6 +40,9 @@ classDiagram
    style json_invalid_iterator fill:#CCCCFF
 ```

+<p class="nj-caption" markdown>Class hierarchy of the library's exceptions; arrows point from a derived class to its
+base class, and the highlighted box is `basic_json::invalid_iterator`.</p>
+
 ## Member functions

 - **what** - returns explanatory string
@@ -75,4 +78,4 @@ classDiagram

 ## Version history

- Since version 3.0.0.
+- Added in version 3.0.0.
@@ -104,8 +104,8 @@ When iterating over an array, `key()` will return the index of the element as st

 ## Version history

- Added `iterator_wrapper` in version 3.0.0.
- Added `items` and deprecated `iterator_wrapper` in version 3.1.0.
+- Added in version 3.1.0 as the replacement of the static function `iterator_wrapper`, which was available since
+  version 1.0.0 and is deprecated since version 3.1.0.
 - Added structured binding support in version 3.5.0.

 !!! warning "Deprecation"
@@ -51,4 +51,4 @@ deserializes. See [Template Parameter Requirements](../../features/types/templat

 ## Version history

- Since version 2.0.0.
+- Added in version 2.1.0.
@@ -71,6 +71,6 @@ returned by `#!cpp (*this)[key]`); it is read as it was when `merge_patch()` was

 ## Version history

- Added in version 3.0.0.
+- Added in version 3.1.0.
 - Fixed use of freed or relocated memory when `apply_patch` is `#!cpp *this` or refers to a value contained in
  `#!cpp *this`, in version 3.13.0.
@@ -128,6 +128,6 @@ interpreted as `object_t::value_type` or `std::initializer_list<basic_json>`, se

 ## Version history

-1. Since version 1.0.0.
-2. Since version 1.0.0.
-3. Since version 2.0.0.
+1. Added in version 1.0.0.
+2. Added in version 1.0.0.
+3. Added in version 2.0.0.
@@ -284,10 +284,10 @@ Strong exception safety: if an exception occurs, the original value stays intact
 1. Added in version 1.0.0. Fixed in version 3.13.0 to throw `#!cpp std::length_error` instead of emptying the array and
   accessing it out of bounds when `idx` equals the maximum value of `size_type`. A missing index in the const version
   is guarded by a runtime assertion since version 3.13.0.
-2. Added in version 1.0.0. Added overloads for `T* key` in version 1.1.0. Removed overloads for `T* key` (replaced by 3)
-   in version 3.11.0.
-3. Added in version 3.11.0. Fixed in version 3.13.0 to consistently accept `std::string_view`-convertible keys, as
-   already supported by [`at`](at.md), [`value`](value.md), [`find`](find.md), and other lookup functions.
+2. Added in version 1.0.0. Added overloads for `T* key` in version 1.1.0. The `T* key` overloads forward to
+   overload 3 since version 3.11.0.
+3. Added in version 3.11.0. Support for keys convertible to `std::string_view` added in version 3.13.0, consistently
+   across the lookup functions.
 4. Added in version 2.0.0. A missing array index in the const version is guarded by a runtime assertion since
   version 3.13.0. Throws [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109) instead of
 [`out_of_range.404`](../../home/exceptions.md#jsonexceptionout_of_range404) for a one-character array index that is not
@@ -89,6 +89,6 @@ Linear in the size of the JSON value.

 ## Version history

- Since version 1.0.0.
+- Added in version 1.0.0.
 - Macros `JSON_EXPLICIT`/[`JSON_USE_IMPLICIT_CONVERSIONS`](../macros/json_use_implicit_conversions.md) added
  in version 3.9.0.
@@ -40,6 +40,9 @@ classDiagram
    style json_other_error fill:#CCCCFF
 ```

+<p class="nj-caption" markdown>Class hierarchy of the library's exceptions; arrows point from a derived class to its
+base class, and the highlighted box is `basic_json::other_error`.</p>
+
 ## Member functions

 - **what** - returns explanatory string
@@ -75,4 +78,4 @@ classDiagram

 ## Version history

- Since version 3.0.0.
+- Added in version 3.0.0.
@@ -41,6 +41,9 @@ classDiagram
    style json_out_of_range fill:#CCCCFF
 ```

+<p class="nj-caption" markdown>Class hierarchy of the library's exceptions; arrows point from a derived class to its
+base class, and the highlighted box is `basic_json::out_of_range`.</p>
+
 ## Member functions

 - **what** - returns explanatory string
@@ -76,4 +79,4 @@ classDiagram

 ## Version history

- Since version 3.0.0.
+- Added in version 3.0.0.
@@ -25,6 +25,10 @@ static basic_json parse(IteratorType first, SentinelType last,
    respectively as UTF-8, UTF-16, and UTF-32. If `SentinelType` differs from `IteratorType`, it must be comparable to
    the iterator type with `operator!=`.

+    Ill-formed UTF-16 and UTF-32 sequences are rejected: a lone surrogate, a high surrogate that is not followed by its
+    low surrogate, and a code point above `U+10FFFF` all yield a
+    [`parse_error.101`](../../home/exceptions.md#jsonexceptionparse_error101).
+
 ## Template parameters

 `InputType`
@@ -34,9 +38,12 @@ static basic_json parse(IteratorType first, SentinelType last,
    - a `FILE` pointer (throws if null)
    - a C-style array of characters
    - a pointer to a null-terminated string of single byte characters (throws if null)
-    - a `std::string`
+    - a `std::string` or a `std::string_view` (C++17)
    - a container `obj` for which `begin(obj)` and `end(obj)` produce a valid pair of iterators
      (as found via ADL or member functions, with semantics compatible to `std::begin` and `std::end`)
+    - wide characters (`wchar_t`, `char16_t`, `char32_t`), which are converted to UTF-8: a wide string object
+      (`std::wstring`, `std::u16string`, `std::u32string`) or an array (e.g. a wide string literal); a pointer to a
+      null-terminated wide string (e.g. `std::u16string::c_str()`) is not supported

 `IteratorType`
 :   a compatible iterator type, for instance.
@@ -112,6 +119,13 @@ By default, a `'\0'` (NUL) byte anywhere in the input is treated as end of input
 outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-bytes-in-the-input) for details and the
 [`JSON_STRICT_NUL_HANDLING`](../macros/json_strict_nul_handling.md) macro to opt into rejecting it instead.

+!!! tip "Parsing into a document instead of a value"
+
+    [`basic_json_document::parse`](../basic_json_document/parse.md) accepts the same inputs and the same options, but
+    keeps the result as a flat index of the parsed values instead of a tree of `basic_json` values. It is faster and uses
+    less memory when only parts of the document are read, and it also accepts a pointer to a null-terminated wide string,
+    which `parse()` does not. See [Zero-copy JSON views](../../features/json_view.md).
+
 !!! tip "Performance"

    Contiguous inputs (strings, string views, vectors, arrays, pointer ranges) are the fastest to parse. A
@@ -250,6 +264,22 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
    --8<-- "examples/trailing_commas.output"
    ```

+??? example "Example: parse from UTF-16, UTF-32, and wide strings"
+
+    The encoding is deduced from the character type of the input; `std::u16string` and `std::u32string` are interpreted
+    as UTF-16 and UTF-32, and `std::wstring` uses the platform's `wchar_t` width. String literals like `u"..."`,
+    `U"..."`, and `L"..."` work as well, as do iterators over wide characters.
+
+    ```cpp
+    --8<-- "examples/parse__wide_string.cpp"
+    ```
+
+    Output:
+
+    ```json
+    --8<-- "examples/parse__wide_string.output"
+    ```
+
 ## See also

 - [accept](accept.md) - check if the input is valid JSON
@@ -280,6 +310,9 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
  time).
 - Parsing from a `FILE*` locks the file once instead of once per character in version 3.13.0
  ([`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md) restores `std::fgetc`).
+- Ill-formed UTF-16 and UTF-32 input (a lone surrogate, a high surrogate that is not followed by its low surrogate, or
+  a code point above `U+10FFFF`) is rejected with `parse_error.101` in version 3.13.0; before that, some such
+  sequences were accepted or ended the input silently.

 !!! warning "Deprecation"

@@ -43,6 +43,9 @@ classDiagram
    style json_parse_error fill:#CCCCFF
 ```

+<p class="nj-caption" markdown>Class hierarchy of the library's exceptions; arrows point from a derived class to its
+base class, and the highlighted box is `basic_json::parse_error`.</p>
+
 ## Member functions

 - **what** - returns explanatory string
@@ -84,4 +87,4 @@ or the end of file. This also holds true when reading a byte vector for binary f

 ## Version history

- Since version 3.0.0.
+- Added in version 3.0.0.
@@ -22,7 +22,12 @@ The parser callback distinguishes the following events:

 ## Examples

-![Example when certain parse events are triggered](../../images/callback_events.png)
+<div class="nj-fig-wrap" markdown>
+--8<-- "images/callback_events.svg"
+</div>
+
+<p class="nj-caption" markdown>Each coloured dot marks where the parser reports a `parse_event_t` event while reading
+the JSON text on the left; the legend on the right names the event per colour.</p>

 ??? example

@@ -23,7 +23,12 @@ table describes the values of the parameters `depth`, `event`, and `parsed`.
 | `parse_event_t::array_end`    | the parser read `]` and finished processing a JSON array  | depth of the parent of the JSON array     | the parsed JSON array            |
 | `parse_event_t::value`        | the parser finished reading a JSON value                  | depth of the value                        | the parsed JSON value            |

-![Example when certain parse events are triggered](../../images/callback_events.png)
+<div class="nj-fig-wrap" markdown>
+--8<-- "images/callback_events.svg"
+</div>
+
+<p class="nj-caption" markdown>Parse events for a small JSON text: each coloured dot marks the position at which the
+parser calls the callback, and the legend on the right names the event per colour.</p>

 Discarding a value (i.e., returning `#!cpp false`) has different effects depending on the context in which function was
 called:
@@ -125,6 +125,6 @@ throws.

 ## Version history

-1. Since version 1.0.0.
-2. Since version 1.0.0.
-3. Since version 2.0.0.
+1. Added in version 1.0.0.
+2. Added in version 1.0.0.
+3. Added in version 2.0.0.
@@ -7,7 +7,13 @@ const_reverse_iterator rbegin() const noexcept;

 Returns an iterator to the reverse-beginning; that is, the last element.

-![Illustration from cppreference.com](../../images/range-rbegin-rend.svg)
+<div class="nj-fig-wrap" markdown>
+--8<-- "images/range-rbegin-rend.svg"
+</div>
+
+<p class="nj-caption" markdown>`rbegin()` points to the last element and `rend()` to the position before the first
+element. The upper row is the reversed sequence and the lower row the forward sequence; dashed arrows link each reverse
+iterator to the forward iterator it stores, and dashed cells are past-the-last positions.</p>

 ## Return value

@@ -8,7 +8,13 @@ const_reverse_iterator rend() const noexcept;
 Returns an iterator to the reverse-end; that is, one before the first element. This element acts as a placeholder,
 attempting to access it results in undefined behavior.

-![Illustration from cppreference.com](../../images/range-rbegin-rend.svg)
+<div class="nj-fig-wrap" markdown>
+--8<-- "images/range-rbegin-rend.svg"
+</div>
+
+<p class="nj-caption" markdown>`rend()` points to the position before the first element and `rbegin()` to the last
+element. The upper row is the reversed sequence and the lower row the forward sequence; dashed arrows link each reverse
+iterator to the forward iterator it stores, and dashed cells are past-the-last positions.</p>

 ## Return value

@@ -31,6 +31,10 @@ Read from input and generate SAX events
    respectively as UTF-8, UTF-16, and UTF-32. If `SentinelType` differs from `IteratorType`, it must be comparable to
    the iterator type with `operator!=`.

+    Ill-formed UTF-16 and UTF-32 sequences are rejected: a lone surrogate, a high surrogate that is not followed by its
+    low surrogate, and a code point above `U+10FFFF` all yield a
+    [`parse_error.101`](../../home/exceptions.md#jsonexceptionparse_error101).
+
 The SAX event lister must follow the interface of [`json_sax`](../json_sax/index.md).

 ## Template parameters
@@ -42,8 +46,12 @@ The SAX event lister must follow the interface of [`json_sax`](../json_sax/index
    - a `FILE` pointer
    - a C-style array of characters
    - a pointer to a null-terminated string of single byte characters
+    - a `std::string` or a `std::string_view` (C++17)
    - a container `obj` for which `begin(obj)` and `end(obj)` produce a valid pair of iterators
      (as found via ADL or member functions, with semantics compatible to `std::begin` and `std::end`)
+    - wide characters (`wchar_t`, `char16_t`, `char32_t`), which are converted to UTF-8: a wide string object
+      (`std::wstring`, `std::u16string`, `std::u32string`) or an array (e.g. a wide string literal); a pointer to a
+      null-terminated wide string (e.g. `std::u16string::c_str()`) is not supported

 `IteratorType`
 :   a compatible iterator type for overload (2); a pair of character iterators whose `value_type` is an integral type
@@ -160,6 +168,9 @@ use the same file with stdio functions, but it must not wait for another thread
  ([`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md)).
 - Parsing from a `FILE*` locks the file once instead of once per character in version 3.13.0
  ([`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md)).
+- Ill-formed UTF-16 and UTF-32 input (a lone surrogate, a high surrogate that is not followed by its low surrogate, or
+  a code point above `U+10FFFF`) is rejected with `parse_error.101` in version 3.13.0; before that, some such
+  sequences were accepted or ended the input silently.

 !!! warning "Deprecation"

@@ -182,10 +182,10 @@ Constant.

 ## Version history

-1. Since version 1.0.0. Exchanges the `json_base_class_t` subobject along with the value since version 3.13.0.
-2. Since version 1.0.0. Exchanges the `json_base_class_t` subobject along with the value since version 3.13.0.
-3. Since version 1.0.0.
-4. Since version 1.0.0.
-5. Since version 1.0.0.
-6. Since version 3.8.0.
-7. Since version 3.8.0.
+1. Added in version 1.0.0. Exchanges the `json_base_class_t` subobject along with the value since version 3.13.0.
+2. Added in version 1.0.0. Exchanges the `json_base_class_t` subobject along with the value since version 3.13.0.
+3. Added in version 1.0.0.
+4. Added in version 1.0.0.
+5. Added in version 1.0.0.
+6. Added in version 3.8.0.
+7. Added in version 3.8.0.
@@ -124,5 +124,3 @@ Linear in the size of the JSON value `j`.
  [`JSON_STRICT_BINARY_UTF8`](../macros/json_strict_binary_utf8.md) is enabled) throws `type_error.316`.
 - Throws `type_error.321` for a discarded value since version 3.13.0; previously, a discarded value nested in an
  array or object was silently skipped, producing invalid BJData.
- Writes unsigned integers wider than 64 bits as high-precision numbers since version 3.13.0; previously, they were
-  silently truncated to 64 bits.
@@ -41,6 +41,9 @@ classDiagram
    style json_type_error fill:#CCCCFF
 ```

+<p class="nj-caption" markdown>Class hierarchy of the library's exceptions; arrows point from a derived class to its
+base class, and the highlighted box is `basic_json::type_error`.</p>
+
 ## Member functions

 - **what** - returns explanatory string
@@ -76,4 +79,4 @@ classDiagram

 ## Version history

- Since version 3.0.0.
+- Added in version 3.0.0.
@@ -231,11 +231,8 @@ changes to any JSON value.
 1. Added in version 1.0.0. Changed parameter `default_value` type from `const ValueType&` to `ValueType&&` in version
   3.11.0. Deleted overload for integral key types added in version 3.13.0 to reject such calls at compile time
   instead of causing undefined behavior at runtime.
-2. Added in version 3.11.0. Made `ValueType` the first template parameter in version 3.11.2. Fixed in version 3.13.0
-   to consistently accept `std::string_view`-convertible keys, as already supported by
-   [`operator[]`](operator[].md), [`at`](at.md), [`find`](find.md), and other lookup functions.
-3. Added in version 2.0.2. Extended to work with arrays in version 3.13.0, including fixing an issue where resolving
-   `ptr` through an array unexpectedly threw `out_of_range` instead of returning the resolved element (or
-   `default_value`, as documented). Throws [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109)
+2. Added in version 3.11.0. Made `ValueType` the first template parameter in version 3.11.2. Support for keys
+   convertible to `std::string_view` added in version 3.13.0, consistently across the lookup functions.
+3. Added in version 2.0.2. Extended to work with arrays in version 3.13.0. Throws [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109)
   instead of returning `default_value` for a one-character array index that is not a digit (e.g., `/x`) in version
   3.13.0, as it already did for longer ones.
@@ -48,6 +48,9 @@ functions [`is_null`](is_null.md), [`is_object`](is_object.md), [`is_array`](is_
        F --> G[binary]
    ```

+    <p class="nj-caption" markdown>Arrows point from a type to the next greater type in the ordering used by
+    `operator<`.</p>
+
 !!! note "Types of numbers"

    There are three enumerators for numbers (`number_integer`, `number_unsigned`, and `number_float`) to distinguish
@@ -9,8 +9,8 @@ class basic_json_document;

 A parsed JSON text, held as a flat index of its values
 ([16 bytes per value](../../home/architecture.md#node-index-of-json-views)) instead of a tree of `BasicJsonType` values.
-Strings and numbers stay in the source text; only strings that contain escapes are decoded, into one buffer owned by
-the document. [`basic_json_view`](../basic_json_view/index.md) is a read-only handle to one value of a
+Strings and floating-point numbers stay in the source text; integers are converted while parsing, and strings that
+contain escapes are decoded into one buffer owned by the document. [`basic_json_view`](../basic_json_view/index.md) is a read-only handle to one value of a
 `basic_json_document`; [`materialize()`](../basic_json_view/materialize.md) turns a subtree into the
 `BasicJsonType` value that [`BasicJsonType::parse()`](../basic_json/parse.md) would have produced for it.

@@ -115,6 +115,13 @@ points apply to every edit:
  [`source_offset()`](../basic_json_view/source_offset.md) of a value introduced by an edit is
  `#!cpp static_cast<std::size_t>(-1)`, the same value it reports for a decoded string.

+## See also
+
+- [Zero-copy JSON views](../../features/json_view.md) - guide to documents and views
+- [**basic_json_view**](../basic_json_view/index.md) - the non-owning handle to a value in a document
+- [**json_document**](../json_document.md) and [**json_editable_document**](../json_editable_document.md) - the default specializations
+- [**materialize**](../basic_json_view/materialize.md) - build a `basic_json` value from a view
+
 ## Version history

 - Added in version 3.13.0.
@@ -21,17 +21,19 @@ static basic_json_document parse(IteratorType first, IteratorType last,

 Both overloads accept the same JSON text as [`BasicJsonType::parse()`](../basic_json/parse.md), with the same
 `ignore_comments`/`ignore_trailing_commas` options, but build a [`basic_json_document`](index.md) (a flat index into
-the input) instead of a tree of `BasicJsonType` values. They take the same inputs as `BasicJsonType::parse()`. Byte
-inputs that stay alive can be borrowed; all others (streams, `#!cpp FILE*`, wide characters, non-contiguous
-iterators) are read into a copy that the document owns -- see the Notes. Use [`parse_copy()`](parse_copy.md) to get an
-owned copy of a borrowable input as well.
+the input) instead of a tree of `BasicJsonType` values. They accept every input `BasicJsonType::parse()` takes, and in
+addition a pointer to a null-terminated wide string (which `BasicJsonType::parse()` rejects). Contiguous inputs of
+single-byte characters that stay alive can be borrowed; all others (streams, `#!cpp FILE*`, wide characters, which
+must be converted to UTF-8, and non-contiguous iterators) are read into a copy that the document owns -- see the
+Notes. Use [`parse_copy()`](parse_copy.md) to get an owned copy of a borrowable input
+as well.

 ## Template parameters

 `InputType`
 :   A compatible input, for instance:

-    - a `#!cpp std::string`, `#!cpp std::string_view`, or a C-style array of single-byte characters
+    - a `#!cpp std::string`, a `#!cpp std::string_view` (C++17), or a C-style array of single-byte characters
    - a pointer to a null-terminated string of single-byte characters (`#!cpp char`, `#!cpp signed char`,
      `#!cpp unsigned char`, `#!cpp std::uint8_t`)
    - a container for which `#!cpp obj.data()` and `#!cpp obj.size()` give contiguous single-byte access, e.g.
@@ -47,6 +49,10 @@ owned copy of a borrowable input as well.
    `#!cpp std::string::iterator`; the iterators of single-byte characters are borrowed or read like the byte inputs
    above, those of wide characters are converted to UTF-8

+Ill-formed UTF-16 and UTF-32 sequences are rejected: a lone surrogate, a high surrogate that is not followed by its low
+surrogate, and a code point above `U+10FFFF` all yield a
+[`parse_error.101`](../../home/exceptions.md#jsonexceptionparse_error101).
+
 ## Parameters

 `input` (in)
@@ -155,3 +161,5 @@ buffer of a given length, pass a pair of pointers: `#!cpp parse(ptr, ptr + len)`
 ## Version history

 - Added in version 3.13.0.
+- Ill-formed UTF-16 and UTF-32 input (a lone surrogate, a high surrogate that is not followed by its low surrogate, or
+  a code point above `U+10FFFF`) is rejected with `parse_error.101`.
@@ -80,7 +80,8 @@ None of these exceptions carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics
   Objects with 128 or more members get a hash index of their keys while parsing, so that a lookup in them takes
   constant time on average.
 2. Linear in `idx`: elements are skipped one at a time from the first one, since they are not a fixed size in the
-   index (unlike `BasicJsonType`'s array, which is random-access).
+   index (unlike `BasicJsonType`'s array, which is random-access). Constant if no element of the array is an array
+   or object, since the elements are then adjacent in the index.
 3. Linear in the number of reference tokens of `ptr` and, for each token, in the number of members of the object at
   that level (as 1.) or the index into the array (as 2.).

@@ -28,7 +28,8 @@ This exception does not carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics.

 Linear in the size of the array or object: unlike [`front()`](front.md), which only ever looks at the first
 element, `back()` has to walk every element to find where they end, since elements are not a fixed size in the
-index.
+index. Constant if no element of the array is an array or object, since the elements are then adjacent
+in the index.

 ## Notes

@@ -143,6 +143,13 @@ still refers to it -- including ones taken before the change -- reads the new va

 - [**source_offset**](source_offset.md) - byte offset of this value in the document's source text

+## See also
+
+- [Zero-copy JSON views](../../features/json_view.md) - guide to documents and views
+- [**basic_json_document**](../basic_json_document/index.md) - the document that owns the parsed data
+- [**json_view**](../json_view.md) and [**json_editable_view**](../json_editable_view.md) - the default specializations
+- [**materialize**](materialize.md) - build a `basic_json` value from a view
+
 ## Version history

 - Added in version 3.13.0.
@@ -86,7 +86,8 @@ None of these exceptions carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics
   Objects with 128 or more members get a hash index of their keys while parsing, so that a lookup in them takes
   constant time on average.
 2. Linear in `idx`: elements are skipped one at a time from the first one, since they are not a fixed size in the
-   index (unlike `BasicJsonType`'s array, which is random-access).
+   index (unlike `BasicJsonType`'s array, which is random-access). Constant if no element of the array is an array
+   or object, since the elements are then adjacent in the index.
 3. Linear in the number of reference tokens of `ptr` and, for each token, in the number of members of the object at
   that level (as 1.) or the index into the array (as 2.).

@@ -51,4 +51,4 @@ byte_container_with_subtype(container_type&& container, subtype_type subtype);

 ## Version history

-Since version 3.8.0.
+Added in version 3.8.0.
@@ -39,4 +39,4 @@ Constant.

 ## Version history

-Since version 3.8.0.
+Added in version 3.8.0.
@@ -42,4 +42,4 @@ Constant.

 ## Version history

-Since version 3.8.0.
+Added in version 3.8.0.
@@ -29,6 +29,14 @@ specific naming scheme in order to override the binary type.
 - [**has_subtype**](has_subtype.md) - return whether the value has a subtype
 - [**clear_subtype**](clear_subtype.md) - clears the binary subtype

+## See also
+
+- [Binary values](../../features/binary_values.md) - how binary values and subtypes are handled
+- [**binary**](../basic_json/binary.md) - create a binary array value
+- [**get_binary**](../basic_json/get_binary.md) - get a reference to the stored binary value
+- [**binary_t**](../basic_json/binary_t.md) - type for binary arrays
+- [Binary formats](../../features/binary_formats/index.md) - formats that can store binary values
+
 ## Version history

 - Added in version 3.8.0.
@@ -44,4 +44,4 @@ Constant.

 ## Version history

-Since version 3.8.0.
+Added in version 3.8.0.
@@ -30,4 +30,4 @@ types.

 ## Version history

-Since version 1.0.0.
+Added in version 1.0.0.
@@ -32,4 +32,4 @@ specialization.

 ## Version history

-Since version 3.13.0.
+Added in version 3.13.0.
@@ -40,4 +40,4 @@ parsing, without ever rewriting the source text -- see [Edits](basic_json_docume

 ## Version history

-Since version 3.13.0.
+Added in version 3.13.0.
@@ -38,4 +38,4 @@ still referring to it seeing the change, see [Edits](basic_json_document/index.m

 ## Version history

-Since version 3.13.0.
+Added in version 3.13.0.
@@ -36,6 +36,9 @@ flowchart LR
    parent["parent_pointer() returns /a/b"] -.-> B
 ```

+<p class="nj-caption" markdown>Boxes are the reference tokens in order; dotted arrows show which token each member
+function reads, removes, or adds to.</p>
+
 The diagram shows the reference tokens of the JSON pointer `/a/b/c`.

 ## Member types
@@ -51,5 +51,5 @@ operator string_t() const

 ## Version history

- Since version 2.0.0.
+- Added in version 2.0.0.
 - Changed type to `string_t` and deprecated in version 3.11.0.
@@ -49,5 +49,5 @@ ptr == json_pointer(ptr.to_string());

 ## Version history

- Since version 2.0.0.
+- Added in version 2.0.0.
 - Changed return type to `string_t` in version 3.11.0.
@@ -25,6 +25,9 @@ sequenceDiagram
    P->>H: end_object()
 ```

+<p class="nj-caption" markdown>Each arrow is one call from the parser to the SAX handler, from top to bottom in the
+order the calls happen.</p>
+
 Note `elements` is passed as `#!cpp std::numeric_limits<std::size_t>::max()` (i.e., "unknown") for JSON text input;
 only binary formats such as CBOR or MessagePack may report the actual number of elements in `start_object`/
 `start_array`. Also note that `1` is reported via `number_unsigned` rather than `number_integer` because it has no
@@ -59,6 +62,13 @@ leading `-` sign.
 - [**start_object**](start_object.md) (_virtual_) - the beginning of an object was read
 - [**string**](string.md) (_virtual_) - a string value was read

+## See also
+
+- [SAX interface](../../features/parsing/sax_interface.md) - guide to event-based parsing
+- [**sax_parse**](../basic_json/sax_parse.md) - generate SAX events from an input
+- [**parse**](../basic_json/parse.md) - DOM parsing, with optional [parser callbacks](../../features/parsing/parser_callbacks.md)
+- [Parse exceptions](../../features/parsing/parse_exceptions.md)
+
 ## Version history

 - Added in version 3.2.0.
@@ -31,4 +31,4 @@ This type is a [`basic_json_view`](basic_json_view/index.md) of a value of a [`j

 ## Version history

-Since version 3.13.0.
+Added in version 3.13.0.
@@ -137,4 +137,13 @@ header. See also the [macro overview page](../../features/macros.md).
 - [**NLOHMANN_DEFINE_DERIVED_TYPE_NON_INTRUSIVE_WITH_DEFAULT_WITH_NAMES**](nlohmann_define_type_with_names.md) - serialize/deserialize
  a derived class; uses default values; uses custom names
 - [**NLOHMANN_DEFINE_DERIVED_TYPE_NON_INTRUSIVE_ONLY_SERIALIZE_WITH_NAMES**](nlohmann_define_type_with_names.md) - serialize a derived
-  class; uses custom names
+  class; uses custom names
+
+## See also
+
+- [Macros](../../features/macros.md) - guide to the supported macros
+- [Runtime assertions](../../features/assertions.md)
+- [Arbitrary type conversions](../../features/arbitrary_types.md) - using the `NLOHMANN_DEFINE_TYPE_*` macros
+- [Enum conversion](../../features/enum_conversion.md) - using `NLOHMANN_JSON_SERIALIZE_ENUM`
+- [The `nlohmann` namespace](../../features/namespace.md)
+- [CMake integration](../../integration/cmake.md) - setting macros from the build system
@@ -38,7 +38,7 @@ Therefore, assertions can be switched off by defining `NDEBUG`.
    ```cpp
    #include <nlohmann/json.hpp>
    
-    using json = nlohmann::json;
+    using nlohmann::json;
    
    int main()
    {
@@ -64,7 +64,7 @@ Therefore, assertions can be switched off by defining `NDEBUG`.
    
    #include <nlohmann/json.hpp>
    
-    using json = nlohmann::json;
+    using nlohmann::json;
    
    int main()
    {
@@ -79,7 +79,7 @@ The default value is `0` (disabled — existing behavior is preserved).
    ```cpp
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -98,7 +98,7 @@ The default value is `0` (disabled — existing behavior is preserved).
    #define JSON_BRACE_INIT_COPY_SEMANTICS 1
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -54,7 +54,7 @@ The default value is `0` (disabled, the deprecated functions can still be called
    ```cpp
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -72,7 +72,7 @@ The default value is `0` (disabled, the deprecated functions can still be called
    #define JSON_DELETE_DEPRECATED_FUNCTIONS 1
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -39,7 +39,7 @@ The default value is `0`.
    #define JSON_DISABLE_ENUM_SERIALIZATION 1
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    enum class Choice
    {
@@ -66,7 +66,7 @@ The default value is `0`.
    #define JSON_DISABLE_ENUM_SERIALIZATION 1
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    enum class Choice
    {
@@ -99,7 +99,7 @@ The default value is `0`.
    #define JSON_DISABLE_ENUM_SERIALIZATION 1
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    enum class Choice
    {
@@ -92,7 +92,7 @@ The default value is `0`: streams are scanned in bulk.
    #include <sstream>
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -115,7 +115,7 @@ The default value is `0`: streams are scanned in bulk.
    #include <sstream>
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -72,7 +72,7 @@ The default value is `0` (disabled — existing behavior is preserved).
    ```cpp
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -89,7 +89,7 @@ The default value is `0` (disabled — existing behavior is preserved).
    #define JSON_DISABLE_TUPLE_REFERENCE_CONVERSION 1
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -73,7 +73,7 @@ The default value is `0`: the file is locked once and read with the unlocked std
    #include <cstdio>
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -92,7 +92,7 @@ The default value is `0`: the file is locked once and read with the unlocked std
    #include <cstdio>
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -61,7 +61,7 @@ By default, `#!cpp JSON_NO_SIMD` is not defined, and vector instructions are use
    #include <iostream>
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -94,7 +94,7 @@ The default value is `0` (disabled — existing behavior is preserved).
    #include <sstream>
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -115,7 +115,7 @@ The default value is `0` (disabled — existing behavior is preserved).
    #include <sstream>
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -64,7 +64,7 @@ The default value is `0` (disabled, the behavior of version 3.12.0 and earlier i
    ```cpp
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -81,7 +81,7 @@ The default value is `0` (disabled, the behavior of version 3.12.0 and earlier i
    #define JSON_STRICT_BINARY_UTF8 1
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -92,7 +92,7 @@ The default value is `0` (disabled — existing behavior is preserved).
    ```cpp
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -109,7 +109,7 @@ The default value is `0` (disabled — existing behavior is preserved).
    #define JSON_STRICT_NUL_HANDLING 1
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    int main()
    {
@@ -77,7 +77,7 @@ The default value is `0` (disabled — existing behavior is preserved).
    #include <map>
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    enum TaskState { TS_STOPPED, TS_RUNNING, TS_COMPLETED };

@@ -105,7 +105,7 @@ The default value is `0` (disabled — existing behavior is preserved).
    #include <map>
    #include <nlohmann/json.hpp>

-    using json = nlohmann::json;
+    using nlohmann::json;

    enum TaskState { TS_STOPPED, TS_RUNNING, TS_COMPLETED };

@@ -42,4 +42,4 @@ parsing an object of `n` keys costs O(n²) rather than O(n log n). See

 ## Version history

-Since version 3.9.0.
+Added in version 3.9.0.
@@ -35,4 +35,4 @@ of object keys, instead of sorting them like [`json_document`](json_document.md)

 ## Version history

-Since version 3.13.0.
+Added in version 3.13.0.
@@ -44,4 +44,4 @@ members [`set`](basic_json_document/set.md) added -- instead of sorting them lik

 ## Version history

-Since version 3.13.0.
+Added in version 3.13.0.
@@ -37,4 +37,4 @@ This type is a [`basic_json_view`](basic_json_view/index.md) of a value of an

 ## Version history

-Since version 3.13.0.
+Added in version 3.13.0.
@@ -32,4 +32,4 @@ This type is a [`basic_json_view`](basic_json_view/index.md) of a value of an

 ## Version history

-Since version 3.13.0.
+Added in version 3.13.0.
@@ -41,6 +41,8 @@ flowchart LR
    E --> F[Trusted caller]
 ```

+<p class="nj-caption" markdown>The trust boundary: untrusted input enters on the left through the parser, the SAX interface, or the binary readers, and only a value tree reaches the trusted caller on the right.</p>
+
 ## Secure design

 - **Strict parsing.** The parser accepts exactly the JSON grammar of [RFC 8259](https://datatracker.ietf.org/doc/html/rfc8259).
@@ -4,6 +4,15 @@ Ensuring quality is paramount for this project, particularly because [numerous o
 depend on it. Each commit to the library undergoes rigorous checks against the following requirements, and any
 violations will result in a failed build.

+The overview shows the checks a change passes on its way from a push or pull request to a release; the sections below
+describe each of them.
+
+<div class="nj-fig-wrap" markdown>
+--8<-- "images/qa_pipeline.svg"
+</div>
+
+<p class="nj-caption" markdown>The checks grouped by the stage at which they run, from push or pull request through the merge into develop to a release. The badge on each card says whether the check runs on every push or PR, on a schedule, or continuously.</p>
+
 ## C++ language compliance and compiler compatibility

 !!! success "Requirement: Compiler support"
@@ -188,10 +197,13 @@ Note: Some modern features (like C++20 ranges or filesystem support) may be disa
        ```

 - [x] The code is checked with the latest [Cppcheck](https://cppcheck.sourceforge.io) with all warnings enabled.
- [x] The code is checked with the latest [Clang Static Analyzer](https://clang-analyzer.llvm.org) with 89 enabled
-  rules.
+- [x] The code is checked with the latest [Clang Static Analyzer](https://clang-analyzer.llvm.org) with 52 enabled
+  checkers.
 - [x] The code is checked with [Infer](https://fbinfer.com).
 - [x] The code is checked with [Codacy](https://app.codacy.com/gh/nlohmann/json/dashboard).
+- [x] The code is scanned with [CodeQL](https://codeql.github.com), [Semgrep](https://semgrep.dev), and
+  [Flawfinder](https://dwheeler.com/flawfinder/) on every push and pull request and on a schedule; the findings are
+  reported to GitHub's code scanning.

 ## Dynamic analysis

@@ -204,6 +216,8 @@ Note: Some modern features (like C++20 ranges or filesystem support) may be disa
 - [x] The test suite is executed with [Valgrind](https://valgrind.org) (Memcheck) to detect memory leaks.
 - [x] The test suite is executed with [Sanitizers](https://github.com/google/sanitizers) (address sanitizer, undefined
  behavior sanitizer, integer overflow detection, nullability violations).
+- [x] The fuzz targets are run with [CIFuzz](https://google.github.io/oss-fuzz/getting-started/continuous-integration/)
+  on every pull request to catch regressions before they are merged.

 ## Dependencies

@@ -223,6 +237,8 @@ Note: Some modern features (like C++20 ranges or filesystem support) may be disa
  No release is made while such an alert is open.
 - [x] Third-party code included in the repository for testing, such as [doctest](https://github.com/doctest/doctest),
  is updated manually.
+- [x] The repository is evaluated with the [OpenSSF Scorecard](https://securityscorecards.dev) on a schedule and on
+  every push to the default branch, and the results are reported to GitHub's code scanning.

 ## Style check

@@ -258,4 +274,21 @@ Note: Some modern features (like C++20 ranges or filesystem support) may be disa
 - [x] The library is tested against relevant CMake versions:
  - CMake 3.5 (the earliest supported)
  - CMake 3.31.6 (the latest 3.x release)
-  - CMake 4.0.0 (a very recent release)
+  - CMake 4.0.0 (the first 4.x release)
+!!! success "Requirement: Other build systems"
+
+    The library can be used with build systems and package managers other than CMake.
+
+- [x] The library can be consumed with [Meson](https://json.nlohmann.me/integration/package_managers/) and the Swift
+  Package Manager; the installation with Meson and the resolution of `Package.swift` are tested in the CI.
+
+!!! success "Requirement: Reproducible and verifiable builds"
+
+    The library can be built and tested without network access or a Git checkout, and its licensing is machine-readable.
+
+- [x] The test suite is executed from an exported source tree without the `.git` directory and with the test data
+  being available offline.
+- [x] The test suite is executed without the tests that change installed files to check that builds are reproducible.
+- [x] The repository is checked for compliance with the [REUSE specification](https://reuse.software) so that the
+  license and copyright of every file is machine-readable.
+- [x] The documentation is built with warnings treated as errors, and its links are checked regularly.
@@ -58,7 +58,7 @@ particular, a 3.x release does not:
 - remove or rename a documented macro, CMake option, CMake target, or header, or change what a documented macro does.

 Exceptions to these rules, for instance when fixing a bug requires changing the exception a function throws, are
-documented in the [release notes](../home/releases.md).
+documented in the [release notes](../home/releases/index.md).

 The following are **not** part of the public API and may change in any release, including patch releases:

@@ -91,6 +91,14 @@ Version 4.0 is therefore the sum of these macros: you can try it on the 3.x rele
 to its 4.0 value and fixing what no longer compiles or behaves differently. Once your code works with all of them, it
 is ready for version 4.0.

+Each macro has a default value in 3.x and a different value in version 4.0. Define the macro to the 4.0 value to try it on the 3.x release train today; version 4.0 makes that value the default:
+
+<div class="nj-fig-wrap" markdown>
+--8<-- "images/roadmap_lanes.svg"
+</div>
+
+<p class="nj-caption" markdown>Each row is one macro: the 3.x release that added it, its default in 3.x, and its value in version 4.0 (highlighted) or "removed". Versions on the 3.x lane are not to scale.</p>
+
 The following macros guard changes that are planned to become the default in version 4.0:

 | Macro                                                                                                            | 3.x default | 4.0 behavior                                                                                                                  | CMake option                                                                                                       | Added  |
@@ -105,6 +113,8 @@ The following macros guard changes that are planned to become the default in ver
 | [`JSON_DISABLE_TUPLE_REFERENCE_CONVERSION`](../api/macros/json_disable_tuple_reference_conversion.md)            | `0`         | `1`: a `basic_json` value can no longer be created from a one-element tuple of a reference to it, such as `std::forward_as_tuple(j)`| [`JSON_DisableTupleReferenceConversion`](../integration/cmake.md#json_disabletuplereferenceconversion)             | 3.13.0 |
 | [`JSON_DELETE_DEPRECATED_FUNCTIONS`](../api/macros/json_delete_deprecated_functions.md)                          | `0`         | removed: the deprecated functions are removed (see below); the `from_*(ptr, len)` overloads stay deleted                      | [`JSON_DeleteDeprecatedFunctions`](../integration/cmake.md#json_deletedeprecatedfunctions)                         | 3.13.0 |

+<p class="nj-table-caption" markdown>Opt-in macros for the version 4.0 behavior. "3.x default" is the value the library uses when the macro is not defined, "Added" is the release that introduced the macro, and – means there is no CMake option.</p>
+
 For example, the following makes a 3.x release behave like version 4.0 with respect to these changes:

 ```cpp
@@ -146,6 +156,8 @@ to the `strict` parameter.
 | Comparing a [`json_pointer`](../api/json_pointer/index.md) with a string via [`operator==`](../api/json_pointer/operator_eq.md) or [`operator!=`](../api/json_pointer/operator_ne.md)                                                              | 3.11.2 | [JSON Pointers](../integration/migration_guide.md#json-pointers)                 |
 | [`from_bjdata`](../api/basic_json/from_bjdata.md) and [`from_bon8`](../api/basic_json/from_bon8.md) with `(ptr, len)`                                                                                                                              | 3.13.0 | [Parsing](../integration/migration_guide.md#parsing)                             |

+<p class="nj-table-caption" markdown>Deprecated functions, with the release that deprecated each one and the section of the migration guide that shows its replacement.</p>
+
 The deprecated legacy comparison of discarded values is controlled by a macro and therefore listed in the table above.

 New breaking changes will follow the same path: they are added to these tables when they land in a 3.x release.
@@ -0,0 +1,782 @@
+/* nlohmann/json brand for Material for MkDocs (values from brand/kit/tokens.css) */
+
+@font-face {
+    font-family: "Inter";
+    src: url("fonts/Inter.woff2") format("woff2");
+    font-weight: 100 900;
+    font-display: swap;
+}
+@font-face {
+    font-family: "Inter";
+    src: url("fonts/Inter-Italic.woff2") format("woff2");
+    font-style: italic;
+    font-weight: 100 900;
+    font-display: swap;
+}
+@font-face {
+    font-family: "JetBrains Mono";
+    src: url("fonts/JetBrainsMono.woff2") format("woff2");
+    font-weight: 100 800;
+    font-display: swap;
+}
+@font-face {
+    font-family: "JetBrains Mono";
+    src: url("fonts/JetBrainsMono-Italic.woff2") format("woff2");
+    font-style: italic;
+    font-weight: 400;
+    font-display: swap;
+}
+
+:root {
+    --md-text-font: "Inter";
+    --md-code-font: "JetBrains Mono";
+}
+
+/* light */
+[data-md-color-scheme="default"] {
+    --nj-blue: #1747a6;
+    --nj-blue-deep: #10357d;
+    --nj-blue-soft: #eaf1fd;
+    --nj-band: #1747a6;
+    --nj-red: #d93a3f;
+    --nj-red-soft: #fdeced;
+    --nj-string: #b4322a;
+    --nj-comment: #646d7a;
+
+    --md-primary-fg-color: var(--nj-band);
+    --md-primary-fg-color--light: #1d55c4;
+    --md-primary-fg-color--dark: #10357d;
+    --md-accent-fg-color: var(--nj-blue-deep);
+    --md-accent-fg-color--transparent: rgba(23, 71, 166, .1);
+    --md-typeset-a-color: var(--nj-blue);
+    --md-default-fg-color: #0f1419;
+    --md-default-fg-color--light: #4a515c;
+    --md-default-fg-color--lighter: #8a919c;
+    --md-default-fg-color--lightest: #e3e6eb;
+    --md-typeset-color: #0f1419;
+    --md-code-bg-color: #f5f7fa;
+    --md-code-fg-color: #0f1419;
+}
+
+/* dark */
+[data-md-color-scheme="slate"] {
+    --nj-blue: #7aa7f5;
+    --nj-blue-deep: #a9c6f8;
+    --nj-blue-soft: #16233b;
+    --nj-band: #173e8c;
+    --nj-red: #f06a6e;
+    --nj-red-soft: #3a1c1e;
+    --nj-string: #f08a7e;
+    --nj-comment: #8b929e;
+
+    --md-hue: 220;
+    --md-primary-fg-color: var(--nj-band);
+    --md-primary-fg-color--light: #163f93;
+    --md-primary-fg-color--dark: #0c2556;
+    --md-accent-fg-color: var(--nj-blue-deep);
+    --md-accent-fg-color--transparent: rgba(122, 167, 245, .12);
+    --md-typeset-a-color: var(--nj-blue);
+    --md-default-bg-color: #0f1218;
+    --md-default-fg-color: #f2f4f7;
+    --md-default-fg-color--light: #b3b9c4;
+    --md-default-fg-color--lighter: #7b828e;
+    --md-default-fg-color--lightest: #272c36;
+    --md-typeset-color: #f2f4f7;
+    --md-code-bg-color: #171b23;
+    --md-code-fg-color: #f2f4f7;
+    --md-footer-bg-color: #0b0e13;
+    --md-footer-bg-color--dark: #08090d;
+}
+
+/* syntax colours (all at least 4.5:1 on the code panel in both schemes) */
+[data-md-color-scheme="default"] {
+    --nj-hl-keyword: #1747a6;
+    --nj-hl-type: #0d6e72;
+    --nj-hl-function: #6b3fb8;
+    --nj-hl-string: #23793a;
+    --nj-hl-escape: #0f5d2a;
+    --nj-hl-key: #10357d;
+    --nj-hl-number: #b04a07;
+    --nj-hl-preproc: #a3247a;
+}
+[data-md-color-scheme="slate"] {
+    --nj-hl-keyword: #7aa7f5;
+    --nj-hl-type: #4fd1c5;
+    --nj-hl-function: #c4a3ff;
+    --nj-hl-string: #7ed491;
+    --nj-hl-escape: #b2ecc0;
+    --nj-hl-key: #a9c6f8;
+    --nj-hl-number: #f5a65b;
+    --nj-hl-preproc: #f48fc8;
+}
+.md-typeset .highlight :is(.k, .kd, .kn, .kr, .kp, .kv, .ow) { color: var(--nj-hl-keyword); font-weight: 600; }
+.md-typeset .highlight :is(.kt, .nc, .nn, .na) { color: var(--nj-hl-type); }
+.md-typeset .highlight :is(.nf, .fm, .nb, .bp) { color: var(--nj-hl-function); }
+.md-typeset .highlight :is(.s, .s1, .s2, .sb, .sc, .sd, .sh, .sx, .sr, .ss, .sa, .dl, .cpf) { color: var(--nj-hl-string); }
+.md-typeset .highlight :is(.se, .si) { color: var(--nj-hl-escape); font-weight: 600; }
+.md-typeset .highlight .nt { color: var(--nj-hl-key); }
+.md-typeset .highlight :is(.m, .mi, .mf, .mh, .mo, .mb, .il, .kc) { color: var(--nj-hl-number); }
+.md-typeset .highlight .kc { font-weight: 500; }
+.md-typeset .highlight .cp { color: var(--nj-hl-preproc); }
+.md-typeset .highlight :is(.c, .c1, .cm, .ch, .cs) { color: var(--nj-comment); font-style: italic; }
+.md-typeset .highlight :is(.o, .p) { color: var(--md-default-fg-color--light); }
+.md-typeset .highlight :is(.n, .nx, .nv, .no, .ni, .nl, .py) { color: var(--md-code-fg-color); }
+.md-typeset .highlight .err { color: inherit; background: none; }
+
+/* typography: Inter with cv11/ss03, bold headlines with negative tracking */
+body {
+    font-feature-settings: "cv11", "ss03";
+}
+.md-typeset {
+    font-size: .85rem;          /* 17 px body */
+    line-height: 1.65;
+}
+.md-typeset h1 {
+    color: var(--md-typeset-color);
+    font-weight: 800;
+    letter-spacing: -.035em;
+    line-height: 1.1;
+}
+.md-typeset h2 {
+    font-weight: 800;
+    letter-spacing: -.025em;
+    line-height: 1.15;
+}
+.md-typeset h3 {
+    font-weight: 700;
+    letter-spacing: -.015em;
+}
+.md-typeset table:not([class]) {
+    font-variant-numeric: tabular-nums;
+}
+
+/* header and tabs: one blue band with the faint syntax pattern; wordmark instead of the site name.
+   A veil over the tile keeps the glyphs from running through the navigation text; the hero shows the pattern at full strength. */
+.md-header, .md-tabs {
+    --nj-veil: linear-gradient(color-mix(in srgb, var(--md-primary-fg-color) 62%, transparent), color-mix(in srgb, var(--md-primary-fg-color) 62%, transparent));
+    background-color: var(--md-primary-fg-color);
+    background-image: var(--nj-veil), url("pattern-on-blue.svg");
+    background-size: auto, 160px 160px;
+    background-position: 0 0, 0 0;
+}
+.md-tabs {
+    background-position: 0 0, 0 -48px;     /* continue the header's tile */
+}
+.md-header__button.md-logo img {
+    width: auto;
+    height: 1.5rem;
+}
+.md-header__topic:first-child .md-ellipsis {   /* the wordmark replaces the site name at every width */
+    display: none;
+}
+@media screen and (max-width: 76.234375em) {   /* Material hides the header logo here: show the wordmark on phones, too */
+    .md-header__button.md-logo {
+        display: block;
+        margin: 0 0 0 .2rem;
+        padding: .4rem .2rem;
+    }
+    .md-header__button[for="__drawer"] {
+        order: -1;
+    }
+}
+.md-nav__button.md-logo img {
+    width: auto;
+    height: 1.4rem;
+}
+
+/* shapes: 6 px corners on blocks, 4 px on inline code */
+.md-typeset pre > code, .md-typeset .highlight, .md-typeset .highlighttable,
+.md-typeset .admonition, .md-typeset details, .md-typeset .tabbed-set,
+.md-typeset .grid.cards > ul > li, .md-typeset .md-button {
+    border-radius: 6px;
+}
+.md-typeset code {
+    border-radius: 4px;
+}
+
+/* inline code: the font alone marks it, no grey box; linked code keeps the link colour */
+.md-typeset :not(pre) > code {
+    padding: 0;
+    background-color: transparent;
+    box-shadow: none;
+    color: inherit;
+    font-size: .88em;
+}
+.md-typeset .highlight pre > code, .md-typeset .highlighttable {
+    border: 1px solid var(--md-default-fg-color--lightest);
+}
+
+/* callouts: 3 px left border; note/info/tip in blue on blue-soft, danger/bug in red on red-soft */
+.md-typeset .admonition, .md-typeset details {
+    border-width: 0 0 0 3px;
+    box-shadow: none;
+    font-size: .8rem;
+}
+.md-typeset :is(.admonition, details):is(.note, .info, .tip, .abstract, .example, .question) {
+    border-color: var(--nj-blue);
+    background-color: var(--nj-blue-soft);
+}
+.md-typeset :is(.note, .info, .tip, .abstract, .example, .question) > :is(.admonition-title, summary) {
+    background-color: transparent;
+}
+.md-typeset :is(.note, .info, .tip, .abstract, .example, .question) > :is(.admonition-title, summary)::before {
+    background-color: var(--nj-blue);
+}
+.md-typeset :is(.admonition, details):is(.danger, .bug, .failure) {
+    border-color: var(--nj-red);
+    background-color: var(--nj-red-soft);
+}
+.md-typeset :is(.danger, .bug, .failure) > :is(.admonition-title, summary) {
+    background-color: transparent;
+}
+.md-typeset :is(.danger, .bug, .failure) > :is(.admonition-title, summary)::before {
+    background-color: var(--nj-red);
+}
+
+/* buttons */
+.md-typeset .md-button--primary {
+    background-color: var(--nj-blue);
+    border-color: var(--nj-blue);
+}
+
+/* home page hero (overrides/home.html): blue band with the syntax pattern, headline, lead, buttons, code panel */
+.nj-hero {
+    --nj-hero-to: #123a8a;
+    color: #fff;
+    background-color: var(--md-primary-fg-color);
+    background-image: url("pattern-on-blue.svg"), linear-gradient(160deg, var(--md-primary-fg-color), var(--nj-hero-to));
+    background-size: 160px 160px, auto;
+    background-position: 0 -96px, 0 0;        /* continue the tile of header and tabs */
+}
+[data-md-color-scheme="slate"] .nj-hero {
+    --nj-hero-to: #0c2556;
+}
+.nj-hero__inner {
+    display: grid;
+    grid-template-columns: minmax(0, 1.1fr) minmax(0, 1fr);
+    gap: 2.4rem;
+    align-items: center;
+    padding: 3rem .8rem 3.6rem;
+}
+.nj-hero__kicker {
+    display: inline-block;
+    margin: 0;
+    padding: .15rem .55rem;
+    border: 1px solid rgba(255, 255, 255, .35);
+    border-radius: 4px;
+    color: #bcd3fb;
+    font-family: var(--md-code-font-family);
+    font-size: .65rem;                         /* 13 px */
+    font-weight: 500;
+    letter-spacing: .02em;
+}
+.nj-hero__title {
+    margin: 0 0 .8rem;
+    color: #fff;
+    font-size: clamp(1.7rem, 4.2vw, 3.2rem);   /* 34-64 px */
+    font-weight: 800;
+    line-height: 1.02;
+    letter-spacing: -.035em;
+}
+.nj-hero__title span {
+    color: #bcd3fb;
+}
+.nj-hero__lead {
+    max-width: 22em;
+    margin: 0 0 2rem;
+    color: rgba(255, 255, 255, .9);
+    font-size: clamp(1.1rem, 2.2vw, 1.6rem);   /* 22-32 px */
+    font-style: italic;
+    font-weight: 500;
+    line-height: 1.35;
+    letter-spacing: -.015em;
+}
+.nj-hero__actions {
+    display: flex;
+    flex-wrap: wrap;
+    gap: .6rem;
+    margin: 0;
+}
+.nj-hero .md-button.nj-hero__button {
+    margin: 0;
+    padding: .55em 1.3em;
+    border: 1px solid rgba(255, 255, 255, .6);
+    border-radius: 6px;
+    color: #fff;
+    font-size: .75rem;
+    font-weight: 600;
+}
+.nj-hero .md-button--primary.nj-hero__button {
+    border-color: #fff;
+    background-color: #fff;
+    color: var(--md-primary-fg-color);
+}
+.nj-hero .md-button.nj-hero__button:is(:hover, :focus) {
+    border-color: #fff;
+    background-color: rgba(255, 255, 255, .12);
+    color: #fff;
+}
+.nj-hero .md-button--primary.nj-hero__button:is(:hover, :focus) {
+    background-color: #eaf1fd;
+    color: var(--md-primary-fg-color);
+}
+.nj-hero__code {
+    border-radius: 6px;
+    background-color: var(--md-code-bg-color);
+    box-shadow: 0 12px 32px rgba(5, 18, 48, .35);
+}
+.nj-hero__code pre {
+    margin: 0;
+    padding: 1.1rem 1.3rem;
+    overflow-x: auto;
+    color: var(--md-code-fg-color);
+    font-family: var(--md-code-font-family);
+    font-size: .7rem;                          /* 14 px */
+    line-height: 1.7;
+}
+.nj-hero__code .nj-k { color: var(--nj-hl-type); }
+.nj-hero__code .nj-s { color: var(--nj-hl-string); }
+.nj-hero__code .nj-n { color: var(--nj-hl-number); }
+.nj-hero__code .nj-c { color: var(--nj-comment); font-style: italic; }
+@media screen and (max-width: 59.984375em) {
+    .nj-hero__inner {
+        grid-template-columns: minmax(0, 1fr);
+        gap: 1.8rem;
+        padding: 2rem .8rem 2.4rem;
+    }
+}
+@media screen and (max-width: 29.984375em) {
+    .nj-hero__code pre {
+        font-size: .6rem;
+    }
+}
+
+/* the hero carries the headline: keep the page's h1 for the title and screen readers only */
+body:has(.nj-hero) .md-content__inner > h1 {
+    position: absolute;
+    width: 1px;
+    height: 1px;
+    overflow: hidden;
+    clip: rect(0 0 0 0);
+    white-space: nowrap;
+}
+
+/* cards: 1 px line border, 6 px corners, blue icon on soft blue, blue border on hover */
+.md-typeset .grid.cards > ul > li {
+    padding: 1rem 1.1rem;
+    border: 1px solid var(--md-default-fg-color--lightest);
+    background-color: var(--md-default-bg-color);
+    transition: border-color 150ms, box-shadow 150ms, transform 150ms;
+}
+.md-typeset .grid.cards > ul > li:is(:hover, :focus-within) {
+    border-color: var(--nj-blue);
+    box-shadow: 0 6px 18px rgba(23, 71, 166, .12);
+    transform: translateY(-1px);
+}
+.md-typeset .grid.cards > ul > li > hr {
+    display: none;
+}
+.md-typeset .grid.cards .twemoji.lg {
+    box-sizing: content-box;
+    margin-right: .5rem;
+    padding: .3rem;
+    border-radius: 6px;
+    background-color: var(--nj-blue-soft);
+    color: var(--nj-blue);
+}
+.md-typeset .grid.cards > ul > li > p:first-child strong {
+    font-size: .9rem;
+    font-weight: 700;
+    letter-spacing: -.01em;
+}
+.md-typeset .grid.cards > ul > li > p:last-child a {
+    font-weight: 600;
+}
+@media (prefers-reduced-motion: reduce) {
+    .md-typeset .grid.cards > ul > li { transition: none; transform: none !important; }
+}
+
+/* home page: no table of contents, so keep the text at reading width and the cards in three columns */
+body:has(.nj-hero) .md-content {
+    max-width: 58rem;
+    margin: 0 auto;
+}
+@media screen and (min-width: 60em) {
+    body:has(.nj-hero) .md-typeset .grid.cards {
+        grid-template-columns: repeat(3, minmax(0, 1fr));
+    }
+}
+
+/* lists: Material's indent, bullets as small blue squares, numbers in the secondary text colour */
+.md-typeset ul:not(.task-list, .md-annotation-list) > li {
+    position: relative;
+    list-style: none;
+}
+.md-typeset ul:not(.task-list, .md-annotation-list) > li::before {
+    content: "";
+    position: absolute;
+    top: .65em;                 /* middle of the first line at line-height 1.65 */
+    left: -.95em;
+    width: .36em;
+    height: .36em;
+    background-color: var(--nj-blue);
+}
+.md-typeset ol > li::marker {
+    color: var(--md-default-fg-color--light);
+    font-variant-numeric: tabular-nums;
+}
+.md-typeset .grid.cards > ul > li::before {
+    display: none;
+}
+
+/* wider page: Material's grid stops at 61rem (1220 px) */
+.md-grid {
+    max-width: 72rem;           /* 1440 px */
+}
+
+/* tables: full width, 1 px line border with 6 px corners, header row on the panel colour, 15 px text */
+.md-typeset__table {
+    display: block;             /* Material: inline-block, so tables only grow to their content */
+}
+.md-typeset table:not([class]) {
+    display: table;
+    width: 100%;
+    border: 1px solid var(--md-default-fg-color--lightest);
+    border-radius: 6px;
+    font-size: .75rem;
+    line-height: 1.55;
+}
+.md-typeset table:not([class]) th {
+    padding: .65em 1em;
+    border-bottom: 1px solid var(--md-default-fg-color--lightest);
+    background-color: var(--md-code-bg-color);
+    color: var(--md-typeset-color);
+    font-weight: 600;
+    vertical-align: bottom;
+}
+.md-typeset table:not([class]) th:first-child { border-top-left-radius: 5px; }
+.md-typeset table:not([class]) th:last-child { border-top-right-radius: 5px; }
+.md-typeset table:not([class]) td {
+    padding: .65em 1em;
+    border-top: 1px solid var(--md-default-fg-color--lightest);
+}
+.md-typeset table:not([class]) tbody tr:first-child td {
+    border-top: 0;
+}
+.md-typeset table:not([class]) tbody tr:hover {
+    background-color: var(--nj-blue-soft);
+    box-shadow: none;
+}
+.md-typeset table:not([class]) td code {
+    white-space: nowrap;
+}
+/* numbers and header code stay on one line; a table wider than the screen scrolls sideways instead */
+.md-typeset table:not([class]) :is(td, th):is([align="right"], [style*="right"]),
+.md-typeset table:not([class]) th code {
+    white-space: nowrap;
+}
+@media screen and (max-width: 44.984375em) {
+    .md-typeset table:not([class]) {
+        font-size: .7rem;
+    }
+    .md-typeset table:not([class]) :is(th, td) {
+        padding: .55em .75em;
+    }
+}
+
+/* more room before headings (Material: h2 1.6em, h3 1.6em, h4-h6 1-1.25em) and at the end of each page (1.2rem) */
+.md-typeset h2 { margin-top: 2.4em; }
+.md-typeset h3 { margin-top: 2.2em; }
+.md-typeset h2 + h3 { margin-top: .8em; }
+.md-typeset :is(h4, h5, h6) { margin-top: 1.8em; }
+.md-content__inner {
+    margin-bottom: 4.8rem;      /* 96 px */
+}
+
+/* Mermaid diagrams: white boxes with a blue outline, grey lines, Inter; shapes and spacing in js/mermaid-brand.js */
+:root > * {
+    --md-mermaid-font-family: var(--md-text-font-family), sans-serif;
+    --md-mermaid-edge-color: var(--md-default-fg-color--lighter);
+    --md-mermaid-node-bg-color: var(--md-default-bg-color);
+    --md-mermaid-node-fg-color: var(--nj-blue);
+    --md-mermaid-label-bg-color: var(--md-default-bg-color);
+    --md-mermaid-label-fg-color: var(--md-default-fg-color);
+    --md-mermaid-sequence-actor-bg-color: var(--nj-blue-soft);
+    --md-mermaid-sequence-actor-line-color: var(--md-default-fg-color--lighter);
+    --md-mermaid-sequence-note-bg-color: var(--md-code-bg-color);
+    --md-mermaid-sequence-note-border-color: var(--md-default-fg-color--lightest);
+    --md-mermaid-sequence-number-fg-color: #fff;
+}
+
+/* a diagram wider than the column scrolls sideways (js/mermaid-brand.js stops shrinking it at 80 %) */
+.md-typeset .mermaid {
+    overflow-x: auto;
+}
+
+
+/* ---- polish pass ---- */
+
+/* header: a search field that reads as a field on the band, tabs with an active marker, readable GitHub facts */
+.md-header .md-search__form {
+    border: 1px solid rgba(255, 255, 255, .22);
+    border-radius: 6px;
+    background-color: rgba(255, 255, 255, .12);
+    transition: background-color 150ms, border-color 150ms;
+}
+.md-header .md-search__form:hover {
+    border-color: rgba(255, 255, 255, .4);
+    background-color: rgba(255, 255, 255, .2);
+}
+.md-search__output {
+    border-radius: 0 0 6px 6px;
+    box-shadow: 0 16px 40px rgba(5, 18, 48, .28);
+}
+.md-search-result__link:focus-visible, .md-search-result__more summary:focus-visible {
+    outline: 2px solid var(--nj-blue);
+    outline-offset: -2px;
+}
+.md-tabs__link {
+    font-size: .72rem;
+    font-weight: 500;
+    opacity: .85;
+}
+.md-tabs__item--active .md-tabs__link, .md-tabs__link:hover {
+    opacity: 1;
+}
+.md-tabs__item--active {
+    box-shadow: inset 0 -2px 0 #fff;
+}
+.md-source__facts {
+    font-size: .62rem;
+}
+
+/* footer: deep brand blue instead of neutral black (the dark scheme keeps its own near-black) */
+[data-md-color-scheme="default"] {
+    --md-footer-bg-color: #0d2a66;
+    --md-footer-bg-color--dark: #0a2152;
+}
+.md-footer-meta .md-copyright, .md-footer-meta .md-copyright a {
+    color: rgba(255, 255, 255, .72);
+}
+.md-footer__link {
+    border-radius: 6px;
+    transition: background-color 150ms;
+}
+.md-footer__link:is(:hover, :focus-visible) {
+    background-color: rgba(255, 255, 255, .08);
+}
+
+/* page title: tighter to the first paragraph; page actions (view/edit source) stay in the background */
+.md-typeset h1 {
+    margin-bottom: 1rem;
+}
+.md-content__button {
+    opacity: .55;
+    transition: opacity 150ms;
+}
+.md-content__button:is(:hover, :focus-visible) {
+    opacity: 1;
+}
+body:has(.nj-hero) .md-content__button {
+    display: none;
+}
+
+/* sidebars: bold marker for the current page, rail and marker for the table of contents */
+.md-nav__link--active {
+    font-weight: 600;
+}
+.md-nav--secondary > .md-nav__list {
+    margin-left: -.1rem;
+    border-left: 1px solid color-mix(in srgb, var(--md-default-fg-color) 16%, transparent);
+}
+.md-nav--secondary .md-nav__link {
+    margin-left: -1px;
+    padding-left: .6rem;
+    border-left: 2px solid transparent;
+}
+.md-nav--secondary .md-nav__link--active {
+    border-left-color: var(--nj-blue);
+    color: var(--nj-blue);
+}
+.md-nav--secondary .md-nav__list .md-nav__list {
+    padding-left: .6rem;
+}
+.md-nav--secondary .md-nav__title {
+    font-size: .64rem;
+    letter-spacing: .04em;
+    text-transform: uppercase;
+}
+
+/* keyboard focus: one visible ring in the brand blue */
+.md-typeset a:focus-visible, .md-typeset .md-button:focus-visible, .md-typeset summary:focus-visible,
+.md-nav__link:focus-visible, .md-tabs__link:focus-visible, .md-top:focus-visible {
+    outline: 2px solid var(--nj-blue);
+    outline-offset: 2px;
+    border-radius: 3px;
+}
+.md-header :is(a, button, label):focus-visible, .nj-hero a:focus-visible {
+    outline: 2px solid #fff;
+    outline-offset: 2px;
+}
+
+/* inline code must not stretch the line box (JetBrains Mono has tall metrics), abbreviations stay quiet */
+.md-typeset :not(pre) > code {
+    line-height: 1;
+}
+.md-typeset abbr {
+    border-bottom-color: var(--md-default-fg-color--lighter);
+}
+.md-typeset :is(h1, h2, h3, h4, a, .grid.cards > ul > li > p:first-child) abbr {
+    border-bottom-color: transparent;
+}
+
+/* number railroad diagram: inline SVG (docs/images/json_syntax_number.svg), follows the colour scheme */
+.md-typeset .railroad-wrap, .md-typeset .nj-fig-wrap {
+    overflow-x: auto;
+    margin: 1.5rem 0;
+}
+.md-typeset svg.railroad {
+    display: block;
+    width: 100%;
+    min-width: 36rem;
+    max-width: 52rem;
+    margin-inline: auto;
+    color: var(--md-default-fg-color);
+    font-family: var(--md-text-font-family), sans-serif;
+}
+.railroad .rr-t { fill: color-mix(in srgb, var(--md-typeset-a-color) 10%, transparent); stroke: var(--md-typeset-a-color); stroke-width: 2; }
+.railroad .rr-track, .railroad .rr-n { stroke: color-mix(in srgb, currentColor 60%, var(--md-default-bg-color)); stroke-opacity: 1; }   /* opaque, so overlapping segments do not darken */
+.railroad .rr-n { fill: color-mix(in srgb, currentColor 6%, transparent); stroke-width: 2; }
+.railroad .rr-bg { fill: var(--md-default-bg-color); }
+.railroad .rr-arrow { fill: currentColor; fill-opacity: .6; }
+.railroad text { fill: currentColor; text-anchor: middle; }
+.railroad .rr-c { font-family: var(--md-code-font-family), monospace; font-size: 16px; font-weight: 500; }
+.railroad .rr-b { font-size: 14.5px; font-weight: 500; }
+.railroad .rr-l { font-size: 14px; text-anchor: start; fill-opacity: .6; }
+.railroad .rr-name { font-size: 17px; font-weight: 700; fill-opacity: 1; }
+/* figures drawn as inline SVG (docs/images/callback_events.svg, range-*.svg): they follow the colour scheme */
+.md-typeset svg.nj-fig {
+    display: block;
+    width: 100%;
+    height: auto;
+    margin-inline: auto;
+    color: var(--md-default-fg-color);
+    font-family: var(--md-text-font-family), sans-serif;
+}
+.md-typeset svg.nj-fig--range { min-width: 30rem; max-width: 40rem; }
+.md-typeset svg.nj-fig--cb { max-width: 30rem; }
+.nj-fig { --fg-line: color-mix(in srgb, currentColor 55%, var(--md-default-bg-color)); }
+.nj-fig .fg-cell { fill: color-mix(in srgb, var(--md-typeset-a-color) 14%, var(--md-default-bg-color)); stroke: var(--fg-line); stroke-width: 1.5; }
+.nj-fig .fg-cell--end { fill: none; stroke-dasharray: 4 3; }
+.nj-fig .fg-pill { fill: color-mix(in srgb, var(--md-typeset-a-color) 10%, var(--md-default-bg-color)); stroke: var(--md-typeset-a-color); stroke-width: 1.5; }
+.nj-fig .fg-pilltext { fill: var(--md-typeset-a-color); font-family: var(--md-code-font-family), monospace; font-size: 14px; font-weight: 500; text-anchor: middle; }
+.nj-fig .fg-arrow { stroke: var(--fg-line); stroke-width: 1.5; fill: none; }
+.nj-fig .fg-arrow--dash { stroke-dasharray: 3 3; }
+.nj-fig .fg-head { fill: var(--fg-line); }
+.nj-fig .fg-note { fill: currentColor; fill-opacity: .7; font-size: 13.5px; text-anchor: middle; }
+.nj-fig .fg-note--r { text-anchor: end; }
+.nj-fig .fg-note--l { text-anchor: start; }
+.nj-fig .fg-h { fill: currentColor; fill-opacity: .7; font-size: 15px; font-weight: 600; }
+.nj-fig .fg-code { fill: currentColor; font-family: var(--md-code-font-family), monospace; font-size: 16px; white-space: pre; }
+.nj-fig .fg-leg { font-size: 15px; }
+.nj-fig { --cb-os: #4eb05a; --cb-oe: #1a6b34; --cb-k: #e5534b; --cb-as: #f0c000; --cb-ae: #b07d00; --cb-v: #1f6fd1; }
+[data-md-color-scheme="slate"] .nj-fig { --cb-os: #7ee787; --cb-oe: #2ea043; --cb-k: #ff7b72; --cb-as: #f2cc60; --cb-ae: #c69026; --cb-v: #58a6ff; }
+.nj-fig .cb-os { fill: var(--cb-os); }
+.nj-fig .cb-oe { fill: var(--cb-oe); }
+.nj-fig .cb-k { fill: var(--cb-k); }
+.nj-fig .cb-as { fill: var(--cb-as); }
+.nj-fig .cb-ae { fill: var(--cb-ae); }
+.nj-fig .cb-v { fill: var(--cb-v); }
+.md-typeset img[src*="json-light"], .md-typeset img[src*="json-dark"] {
+    border-radius: 8px;
+}
+.md-typeset img {
+    max-width: 100%;
+    height: auto;
+}
+
+/* home page: content uses the same column as every other page */
+body:has(.nj-hero) .md-content {
+    max-width: none;
+    margin: 0;
+}
+.md-typeset .grid.cards {
+    width: auto;
+}
+
+/* 404 page (overrides/404.html) */
+.nj-404 {
+    max-width: 30rem;
+    padding: 2rem 0 3rem;
+}
+.nj-404__code {
+    margin: 0 0 .4rem;
+    color: var(--nj-blue);
+    font-family: var(--md-code-font-family);
+    font-size: .8rem;
+    font-weight: 500;
+}
+.md-typeset .nj-404 h1 {
+    margin-bottom: .8rem;
+}
+.nj-404 .md-button {
+    margin: .4rem .4rem 0 0;
+}
+
+/* touch targets and phones */
+@media screen and (max-width: 59.984375em) {
+    .md-nav__link {
+        padding-block: .2rem;
+    }
+}
+@media screen and (max-width: 29.984375em) {
+    .md-typeset h1 {
+        font-size: 1.7em;
+    }
+    .md-typeset .highlight pre > code {
+        font-size: .68rem;
+    }
+}
+
+/* figure captions: "Figure N." in bold, close to the figure, set in from the text column; figures and tables are
+   numbered per page, each with its own counter */
+.md-content__inner { counter-reset: nj-figure nj-table; }
+.md-typeset :is(.nj-caption, .nj-charts-caption) {
+    max-width: none;
+    margin: .3rem 2rem 1.5rem;
+    font-size: .75rem;
+    line-height: 1.5;
+    text-align: left;
+    color: var(--md-default-fg-color--light);
+}
+.md-typeset :is(.nj-fig-wrap, .railroad-wrap, .nj-charts-grid-wrap) + :is(.nj-caption, .nj-charts-caption) { margin-top: -1.1rem; }
+.md-typeset .nj-charts-grid-wrap + :is(.nj-caption, .nj-charts-caption) { margin-top: .3rem; }
+.md-typeset :is(.nj-caption, .nj-charts-caption)::before {
+    counter-increment: nj-figure;
+    content: "Figure " counter(nj-figure) ". ";
+    font-weight: 700;
+    color: var(--md-default-fg-color);
+}
+@media screen and (max-width: 44.9375em) {
+    .md-typeset :is(.nj-caption, .nj-charts-caption) { margin-inline: 1rem; }
+}
+
+/* table captions: "Table N." in bold, directly below the table, in the figure caption style */
+.md-typeset .nj-table-caption {
+    max-width: none;
+    margin: .3rem 2rem 1.5rem;
+    font-size: .75rem;
+    line-height: 1.5;
+    text-align: left;
+    color: var(--md-default-fg-color--light);
+}
+.md-typeset :is(.md-typeset__scrollwrap, .md-typeset__table) + .nj-table-caption { margin-top: -.4rem; }
+.md-typeset .nj-table-caption::before {
+    counter-increment: nj-table;
+    content: "Table " counter(nj-table) ". ";
+    font-weight: 700;
+    color: var(--md-default-fg-color);
+}
+@media screen and (max-width: 44.9375em) {
+    .md-typeset .nj-table-caption { margin-inline: 1rem; }
+}