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+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+.. c:namespace:: DTV.ca
+
+.. _CA_SET_DESCR:
+
+============
+CA_SET_DESCR
+============
+
+Name
+----
+
+CA_SET_DESCR
+
+Synopsis
+--------
+
+.. c:macro:: CA_SET_DESCR
+
+``int ioctl(fd, CA_SET_DESCR, struct ca_descr *desc)``
+
+Arguments
+---------
+
+``fd``
+  File descriptor returned by a previous call to :c:func:`open()`.
+
+``msg``
+  Pointer to struct :c:type:`ca_descr`.
+
+Description
+-----------
+
+CA_SET_DESCR is used for feeding descrambler CA slots with descrambling
+keys (referred as control words).
+
+Return Value
+------------
+
+On success 0 is returned.
+
+On error -1 is returned, and the ``errno`` variable is set
+appropriately.
+
+Generic error codes are described at the
+:ref:`Generic Error Codes <gen-errors>` chapter.