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+PR_GetUniqueIdentity
+====================
+
+Asks the runtime to allocate a unique identity for a layer identified by
+the layer's name.
+
+
+Syntax
+------
+
+.. code::
+
+   #include <prio.h>
+
+   PRDescIdentity PR_GetUniqueIdentity(const char *layer_name);
+
+
+Parameter
+~~~~~~~~~
+
+The function has the following parameter:
+
+``layer_name``
+   The string associated with the creation of a layer's identity.
+
+
+Returns
+~~~~~~~
+
+The function returns one of the following values:
+
+-  If successful, the :ref:`PRDescIdentity` for the layer associated with
+   the string specified in the layer named ``layer_name``.
+-  If the function cannot allocate enough dynamic memory, it fails and
+   returns the value ``PR_INVALID_IO_LAYER`` with the error code
+   ``PR_OUT_OF_MEMORY_ERROR``.
+
+
+Description
+-----------
+
+A string may be associated with a layer when the layer is created.
+:ref:`PR_GetUniqueIdentity` allocates a unique layer identity and
+associates it with the string. The string can be subsequently passed to
+:ref:`PR_CreateIOLayerStub` to create a new file descriptor of that layer.
+
+Call :ref:`PR_GetUniqueIdentity` only once for any particular layer name.
+If you're creating a custom I/O layer, cache the result, and then use
+that cached result every time you call :ref:`PR_CreateIOLayerStub`.