+.SH HISTORY
+SVr3 introduced these functions:
+ slk_clear
+ slk_init
+ slk_label
+ slk_noutrefresh
+ slk_refresh
+ slk_restore
+ slk_set
+ slk_touch
+.PP
+SVr4 added these functions:
+ slk_attroff
+ slk_attron
+ slk_attrset
+ slk_start
+.PP
+X/Open Curses added these:
+ slk_attr_off
+ slk_attr_on
+ slk_attr_set
+ slk_color
+ slk_wset
+.SH EXTENSIONS
+.PP
+X/Open Curses documents the \fIopts\fP argument as reserved for future use,
+saying that it must be null.
+This implementation
+uses that parameter in ABI 6 for the functions which have a color-pair
+parameter to support extended color pairs.
+.PP
+For functions which modify the color, e.g., \fBslk_attr_set\fP,
+if \fIopts\fP is set it is treated as a pointer to \fBint\fP,
+and used to set the color pair instead of the \fBshort\fP pair parameter.