This change includes the following:

* Adds clarifying information about the scope of features to /editions/features.md
* Adds information about Proto Python being able to generate `.pyi` files in /getting-started/pythontutorial.md
* Changes wording in /overview.md regarding the components that make up protocol buffers
* Adds information about how `java_package` and `java_alt_api_package` options are interpreted to /reference/java/java-proto-names.md
* Adds a new topic, /reference/protobuf/edition-2023-spec.md
* Updates /support/version-support.md to reflect the end of support for 3.21.x in C++

PiperOrigin-RevId: 622020800
Change-Id: Ia9a06a1fadfb6c138ea8828fc1537d42ea7ca604

Author: Protocol Buffer Team

content/editions/features.md

@@ -24,6 +24,36 @@ act like proto2 or proto3 files. For more information on how Editions and
 Features work together to set behavior, see
 [Protobuf Editions Overview](/editions/overview).
 
+Each of the following sections has an entry for what scope the feature applies
+to. This can include file, enum, message, or field. The following sample shows a
+mock feature applied to each scope:
+
+```proto
+edition = "2023";
+
+// File-scope definition
+option features.bar = BAZ;
+
+enum Foo {
+  // Enum-scope definition
+  option features.bar = QUX;
+
+  A = 1;
+  B = 2;
+}
+
+message Corge {
+  // Message-scope definition
+  option features.bar = QUUX;
+
+  // Field-scope definition
+  Foo A = 1 [features.bar = GRAULT];
+}
+```
+
+In this example, the setting `GRAULT` in the field-scope feature definition
+overrides the message-scope QUUX setting.
+
 ### `features.enum_type` {#enum_type}
 
 This feature sets the behavior for how enum values that aren't contained within
@@ -38,7 +68,7 @@ and after of a proto3 file.
     unknown field set.
 *   `OPEN:` Open enums parse out of range values into their fields directly.
 
-**Applicable to the following elements:** File, Enum
+**Applicable to the following scopes:** File, Enum
 
 **Default behavior in Edition 2023:** `OPEN`
 
@@ -90,7 +120,7 @@ whether a protobuf field has a value.
     serialized onto the wire (even if it is explicitly set). `has_*` functions
     are not generated for fields set to `IMPLICIT`.
 
-**Applicable to the following elements:** File, Field
+**Applicable to the following scopes:** File, Field
 
 **Default value in the Edition 2023:** `EXPLICIT`
 
@@ -169,7 +199,7 @@ and after of a proto3 file. Editions behavior matches the behavior in proto3.
     JSON. Certain protos are allowed that can result in unspecified behavior at
     runtime (such as many:1 or 1:many mappings).
 
-**Applicable to the following elements:** File, Message, Enum
+**Applicable to the following scopes:** File, Message, Enum
 
 **Default behavior in Edition 2023:** `ALLOW`
 
@@ -215,7 +245,7 @@ and after of a proto3 file.
 *   `DELIMITED`: Message-typed fields are encoded as
     [groups](/programming-guides/proto2#groups).
 
-**Applicable to the following elements:** File, Field
+**Applicable to the following scopes:** File, Field
 
 **Default behavior in Edition 2023:** `LENGTH_PREFIXED`
 
@@ -264,7 +294,7 @@ for `repeated` fields has been migrated to in Editions.
 *   `EXPANDED`: `Repeated` fields are each encoded with the field number for
     each value.
 
-**Applicable to the following elements:** File, Field
+**Applicable to the following scopes:** File, Field
 
 **Default behavior in Edition 2023:** `PACKED`
 
@@ -335,7 +365,7 @@ and after of a proto3 file.
     Parsers may handle this type of field in an unpredictable way, such as
     replacing invalid characters. This is the default proto2 behavior.
 
-**Applicable to the following elements:** File, Field
+**Applicable to the following scopes:** File, Field
 
 **Default behavior in Edition 2023:** `VERIFY`
 
@@ -387,7 +417,7 @@ before and after of a proto3 file.
 *   `true`: Treats the enum as closed regardless of [`enum_type`](#enum_type).
 *   `false`: Respect whatever is set in the `enum_type`.
 
-**Applicable to the following elements:** File, Field
+**Applicable to the following scopes:** File, Field
 
 **Default behavior in Edition 2023:** `false`
 
@@ -442,7 +472,7 @@ before and after of a proto3 file.
 *   `VERIFY`: Overrides the file-level `features.utf8_validation` setting to
     force it to `VERIFY` for Java only.
 
-**Applicable to the following elements:** Field, File
+**Applicable to the following scopes:** Field, File
 
 **Default behavior in Edition 2023:** `DEFAULT`
 

content/getting-started/pythontutorial.md

@@ -195,7 +195,10 @@ compiler `protoc` on your `.proto`:
     Because you want Python classes, you use the `--python_out` option --
     similar options are provided for other supported languages.
 
-This generates `addressbook_pb2.py` in your specified destination directory.
+    Protoc is also able to generate python stubs (`.pyi`) with `--pyi_out`.
+
+This generates `addressbook_pb2.py` (or `addressbook_pb2.pyi`) in your specified
+destination directory.
 
 ## The Protocol Buffer API {#protobuf-api}
 

content/overview.md

@@ -13,8 +13,9 @@ of data streams and using a variety of languages.
 
 Protocol buffers are a combination of the definition language (created in
 `.proto` files), the code that the proto compiler generates to interface with
-data, language-specific runtime libraries, and the serialization format for data
-that is written to a file (or sent across a network connection).
+data, language-specific runtime libraries, the serialization format for data
+that is written to a file (or sent across a network connection), and the
+serialized data.
 
 ## What Problems do Protocol Buffers Solve? {#solve}
 

content/reference/java/java-proto-names.md

@@ -10,6 +10,13 @@ This document contains information on what the fully-qualified Java name of a
 proto is, based on the different proto options. This name corresponds to the
 package you need to import to use that message.
 
+**NOTE:** The `java_package` and `java_alt_api_package` options are interpreted
+relative to the API indicated by `java_api_version`. For example, if
+`java_api_version` is 1, then the proto1 package will be `java_package` and the
+proto2 package (the "alternative" API) will be `java_alt_api_package`. And if
+`java_api_version` is 2, then `java_package` determines the proto2 package and
+`java_alt_api_package` determines the proto1 package.
+
 ## Immutable API Message Names { #immutable-api-message-names }
 
 The names for protos generated by the immutable API (`java_proto_library` BUILD