- <para>If the <literal>seat</literal> parameter of any
- of these functions is passed as NULL the operation is
- executed for the seat of the session of the calling
- process, if there is any.</para>
+ <para><function>sd_seat_can_tty()</function> may be
+ used to determine whether a specific seat provides TTY
+ functionality, i.e. is useful as a text console.</para>
+
+ <para><function>sd_seat_can_graphical()</function> may
+ be used to determine whether a specific seat provides
+ graphics functionality, i.e. is useful as a graphics
+ display.</para>
+
+ <para>If the <varname>seat</varname> parameter of any
+ of these functions is passed as
+ <constant>NULL</constant>, the operation is executed
+ for the seat of the session of the calling process, if
+ there is any.</para>