+SVr4 curses had support for the mouse in a variant of \fBxterm\fP.
+It is mentioned in a few places, but with no supporting documentation:
+.bP
+the \*(``libcurses\*('' manual page lists functions for this feature
+which are prototyped in \fBcurses.h\fP:
+.NS
+extern int mouse_set(long int);
+extern int mouse_on(long int);
+extern int mouse_off(long int);
+extern int request_mouse_pos(void);
+extern int map_button(unsigned long);
+extern void wmouse_position(WINDOW *, int *, int *);
+extern unsigned long getmouse(void), getbmap(void);
+.NE
+.bP
+the \*(``terminfo\*('' manual page lists capabilities for the feature
+.NS
+buttons btns BT Number of buttons on the mouse
+get_mouse getm Gm Curses should get button events
+key_mouse kmous Km 0631, Mouse event has occurred
+mouse_info minfo Mi Mouse status information
+req_mouse_pos reqmp RQ Request mouse position report
+.NE
+.bP
+the interface made assumptions (as does ncurses) about the escape sequences
+sent to and received from the terminal.
+.IP
+For instance
+the SVr4 curses library used the \fBget_mouse\fP capability to tell the
+terminal which mouse button events it should send,
+passing the mouse-button bit-mask to the terminal.
+Also, it could ask the terminal
+where the mouse was using the \fBreq_mouse_pos\fP capability.
+.IP
+Those features required a terminal which had been modified to work with curses.
+They were not part of the X Consortium's xterm.
+.PP
+When developing the xterm mouse support for ncurses in September 1995,
+Eric Raymond was uninterested in using the same interface due to its
+lack of documentation.
+Later, in 1998, Mark Hesseling provided support in
+PDCurses 2.3 using the SVr4 interface.
+PDCurses, however, does not use video terminals,
+making it unnecessary to be concerned about compatibility with the
+escape sequences.
+.PP