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+PR_MemUnmap
+===========
+
+Unmap a memory region that is backed by a memory-mapped file.
+
+
+Syntax
+------
+
+.. code::
+
+   #include <prio.h>
+
+   PRStatus PR_MemUnmap(
+     void *addr,
+     PRUint32 len);
+
+
+Parameters
+~~~~~~~~~~
+
+The function has the following parameters:
+
+``addr``
+   The starting address of the memory region to be unmapped.
+``len``
+   The length, in bytes, of the memory region.
+
+
+Returns
+~~~~~~~
+
+The function returns one of the following values:
+
+-  If the memory region is successfully unmapped, ``PR_SUCCESS``.
+-  If the memory region is not successfully unmapped, ``PR_FAILURE``.
+   The error code can be retrieved via :ref:`PR_GetError`.
+
+
+Description
+-----------
+
+:ref:`PR_MemUnmap` removes the file mapping for the memory region
+(``addr``, ``addr + len``). The parameter ``addr`` is the return value
+of an earlier call to :ref:`PR_MemMap`.