#3753: document that s* etc. are newer and preferred to s#.
diff --git a/Doc/c-api/arg.rst b/Doc/c-api/arg.rst
index de7b930..c3d051a 100644
--- a/Doc/c-api/arg.rst
+++ b/Doc/c-api/arg.rst
@@ -32,42 +32,46 @@
converted to C strings using the default encoding. If this conversion fails, a
:exc:`UnicodeError` is raised.
-``s#`` (string, Unicode or any read buffer compatible object) [const char \*, int]
- This variant on ``s`` stores into two C variables, the first one a pointer to a
- character string, the second one its length. In this case the Python string may
- contain embedded null bytes. Unicode objects pass back a pointer to the default
- encoded string version of the object if such a conversion is possible. All
- other read-buffer compatible objects pass back a reference to the raw internal
- data representation.
-
``s*`` (string, Unicode, or any buffer compatible object) [Py_buffer \*]
- Similar to ``s#``, this code fills a Py_buffer structure provided by the caller.
- The buffer gets locked, so that the caller can subsequently use the buffer even
- inside a ``Py_BEGIN_ALLOW_THREADS`` block; the caller is responsible for calling
- ``PyBuffer_Release`` with the structure after it has processed the data.
+ This is similar to ``s``, but the code fills a :ctype:`Py_buffer` structure
+ provided by the caller. In this case the Python string may contain embedded
+ null bytes. Unicode objects pass back a pointer to the default encoded
+ string version of the object if such a conversion is possible. The
+ underlying buffer is locked, so that the caller can subsequently use the
+ buffer even inside a ``Py_BEGIN_ALLOW_THREADS`` block. **The caller is
+ responsible** for calling ``PyBuffer_Release`` with the structure after it
+ has processed the data.
+
+``s#`` (string, Unicode or any read buffer compatible object) [const char \*, int]
+ This variant on ``s*`` stores into two C variables, the first one a pointer
+ to a character string, the second one its length. All other read-buffer
+ compatible objects pass back a reference to the raw internal data
+ representation. Since this format doesn't allow writable buffer compatible
+ objects like byte arrays, ``s*`` is to be preferred.
``y`` (bytes object) [const char \*]
- This variant on ``s`` convert a Python bytes object to a C pointer to a
- character string. The bytes object must not contain embedded NUL bytes; if it
- does, a :exc:`TypeError` exception is raised.
-
-``y#`` (bytes object) [const char \*, int]
- This variant on ``s#`` stores into two C variables, the first one a pointer to a
- character string, the second one its length. This only accepts bytes objects.
+ This variant on ``s`` converts a Python bytes or bytearray object to a C
+ pointer to a character string. The bytes object must not contain embedded
+ NUL bytes; if it does, a :exc:`TypeError` exception is raised.
``y*`` (bytes object) [Py_buffer \*]
This is to ``s*`` as ``y`` is to ``s``.
+``y#`` (bytes object) [const char \*, int]
+ This variant on ``s#`` stores into two C variables, the first one a pointer
+ to a character string, the second one its length. This only accepts bytes
+ objects, no byte arrays.
+
``z`` (string or ``None``) [const char \*]
Like ``s``, but the Python object may also be ``None``, in which case the C
pointer is set to *NULL*.
-``z#`` (string or ``None`` or any read buffer compatible object) [const char \*, int]
- This is to ``s#`` as ``z`` is to ``s``.
-
``z*`` (string or ``None`` or any buffer compatible object) [Py_buffer*]
This is to ``s*`` as ``z`` is to ``s``.
+``z#`` (string or ``None`` or any read buffer compatible object) [const char \*, int]
+ This is to ``s#`` as ``z`` is to ``s``.
+
``u`` (Unicode object) [Py_UNICODE \*]
Convert a Python Unicode object to a C pointer to a NUL-terminated buffer of
16-bit Unicode (UTF-16) data. As with ``s``, there is no need to provide
@@ -249,6 +253,9 @@
or use ``w#`` instead. Only single-segment buffer objects are accepted;
:exc:`TypeError` is raised for all others.
+``w*`` (read-write byte-oriented buffer) [Py_buffer \*]
+ This is to ``w`` what ``s*`` is to ``s``.
+
``w#`` (read-write character buffer) [char \*, int]
Like ``s#``, but accepts any object which implements the read-write buffer
interface. The :ctype:`char \*` variable is set to point to the first byte of
@@ -256,9 +263,6 @@
single-segment buffer objects are accepted; :exc:`TypeError` is raised for all
others.
-``w*`` (read-write byte-oriented buffer) [Py_buffer \*]
- This is to ``w`` what ``s*`` is to ``s``.
-
``(items)`` (tuple) [*matching-items*]
The object must be a Python sequence whose length is the number of format units
in *items*. The C arguments must correspond to the individual format units in