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+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+.. c:namespace:: DTV.ca
+
+.. _ca_fopen:
+
+====================
+Digital TV CA open()
+====================
+
+Name
+----
+
+Digital TV CA open()
+
+Synopsis
+--------
+
+.. c:function:: int open(const char *name, int flags)
+
+Arguments
+---------
+
+``name``
+  Name of specific Digital TV CA device.
+
+``flags``
+  A bit-wise OR of the following flags:
+
+.. tabularcolumns:: |p{2.5cm}|p{15.0cm}|
+
+.. flat-table::
+    :header-rows:  0
+    :stub-columns: 0
+    :widths: 1 16
+
+    -  - ``O_RDONLY``
+       - read-only access
+
+    -  - ``O_RDWR``
+       - read/write access
+
+    -  - ``O_NONBLOCK``
+       - open in non-blocking mode
+         (blocking mode is the default)
+
+Description
+-----------
+
+This system call opens a named ca device (e.g. ``/dev/dvb/adapter?/ca?``)
+for subsequent use.
+
+When an ``open()`` call has succeeded, the device will be ready for use. The
+significance of blocking or non-blocking mode is described in the
+documentation for functions where there is a difference. It does not
+affect the semantics of the ``open()`` call itself. A device opened in
+blocking mode can later be put into non-blocking mode (and vice versa)
+using the ``F_SETFL`` command of the ``fcntl`` system call. This is a
+standard system call, documented in the Linux manual page for fcntl.
+Only one user can open the CA Device in ``O_RDWR`` mode. All other
+attempts to open the device in this mode will fail, and an error code
+will be returned.
+
+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.