Closes #10142: Support for SEEK_HOLE/SEEK_DATA
diff --git a/Doc/library/io.rst b/Doc/library/io.rst
index e30a016..1d3d702 100644
--- a/Doc/library/io.rst
+++ b/Doc/library/io.rst
@@ -291,6 +291,11 @@
       .. versionadded:: 3.1
          The ``SEEK_*`` constants.
 
+      .. versionadded:: 3.3
+         Some operating systems could support additional values, like
+         :data:`os.SEEK_HOLE` or :data:`os.SEEK_DATA`. The valid values
+         for a file could depend on it being open in text or binary mode.
+
    .. method:: seekable()
 
       Return ``True`` if the stream supports random access.  If ``False``,
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index 28cf4b4..0be5595 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -995,6 +995,10 @@
    Parameters to the :func:`lseek` function. Their values are 0, 1, and 2,
    respectively. Availability: Windows, Unix.
 
+   .. versionadded:: 3.3
+      Some operating systems could support additional values, like
+      :data:`os.SEEK_HOLE` or :data:`os.SEEK_DATA`.
+
 
 .. function:: mkdirat(dirfd, path, mode=0o777)