+<footnote><para>The use of <constant>V4L2_CID_PRIVATE_BASE</constant>
+is problematic because different drivers may use the same
+<constant>V4L2_CID_PRIVATE_BASE</constant> ID for different controls.
+This makes it hard to programatically set such controls since the meaning
+of the control with that ID is driver dependent. In order to resolve this
+drivers use unique IDs and the <constant>V4L2_CID_PRIVATE_BASE</constant>
+IDs are mapped to those unique IDs by the kernel. Consider these
+<constant>V4L2_CID_PRIVATE_BASE</constant> IDs as aliases to the real
+IDs.</para>
+<para>Many applications today still use the <constant>V4L2_CID_PRIVATE_BASE</constant>
+IDs instead of using &VIDIOC-QUERYCTRL; with the <constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant>
+flag to enumerate all IDs, so support for <constant>V4L2_CID_PRIVATE_BASE</constant>
+is still around.</para></footnote>