#4441: improve doc for os.open() flags.
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index 1cb450b..6136e41 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -681,10 +681,11 @@
:func:`fdopen`, or :data:`sys.stdout` or :data:`sys.stderr`, use its :meth:`write`
method.
-The following data items are available for use in constructing the *flags*
-parameter to the :func:`open` function. Some items will not be available on all
-platforms. For descriptions of their availability and use, consult
-:manpage:`open(2)`.
+The following constants are options for the *flags* parameter to the
+:func:`open` function. They can be combined using the bitwise OR operator
+``|``. Some of them are not available on all platforms. For descriptions of
+their availability and use, consult the :manpage:`open(2)` manual page or the
+respective documentation for your operating system.
.. data:: O_RDONLY
@@ -695,8 +696,7 @@
O_EXCL
O_TRUNC
- Options for the *flag* argument to the :func:`open` function. These can be
- combined using the bitwise OR operator ``|``. Availability: Unix, Windows.
+ These constants are available on Unix and Windows.
.. data:: O_DSYNC
@@ -708,8 +708,7 @@
O_SHLOCK
O_EXLOCK
- More options for the *flag* argument to the :func:`open` function. Availability:
- Unix.
+ These constants are only available on Unix.
.. data:: O_BINARY
@@ -720,8 +719,7 @@
O_SEQUENTIAL
O_TEXT
- Options for the *flag* argument to the :func:`open` function. These can be
- combined using the bitwise OR operator ``|``. Availability: Windows.
+ These constants are only available on Windows.
.. data:: O_ASYNC
@@ -730,8 +728,8 @@
O_NOFOLLOW
O_NOATIME
- Options for the *flag* argument to the :func:`open` function. These are
- GNU extensions and not present if they are not defined by the C library.
+ These constants are GNU extensions and not present if they are not defined by
+ the C library.
.. data:: SEEK_SET