- The XSI Curses standard, Issue 4, describes these func-
- tions. It changes the argument type of the attribute-ma-
- nipulation functions <STRONG>slk_attron</STRONG>, <STRONG>slk_attroff</STRONG>, <STRONG>slk_attrset</STRONG>
- to be <STRONG>attr_t</STRONG>, and adds <STRONG>const</STRONG> qualifiers. The format codes
- <STRONG>2</STRONG> and <STRONG>3</STRONG> for <STRONG>slk_init()</STRONG> and the function <STRONG>slk_attr</STRONG> are spe-
- cific to ncurses.
+ The XSI Curses standard, Issue 4, described the soft-key
+ functions, with some differences from SVr4 curses:
+
+ <STRONG>o</STRONG> It added functions like the SVr4 attribute-manipula-
+ tion functions <STRONG>slk_attron</STRONG>, <STRONG>slk_attroff</STRONG>, <STRONG>slk_attrset</STRONG>,
+ but which use <STRONG>attr_t</STRONG> parameters (rather than <STRONG>chtype</STRONG>),
+ along with a reserved <EM>opts</EM> parameter.
+
+ Two of these new functions (unlike the SVr4 functions)
+ have no provision for color: <STRONG>slk_attr_on</STRONG> and <STRONG>slk_at-</STRONG>
+ <STRONG>tr_off</STRONG>.
+
+ The third function (<STRONG>slk_attr_set</STRONG>) has a color-pair pa-
+ rameter.
+
+ <STRONG>o</STRONG> It added <STRONG>const</STRONG> qualifiers to parameters (unnecessari-
+ ly), and
+
+ <STRONG>o</STRONG> It added <STRONG>slk_color</STRONG>.
+
+ The format codes <STRONG>2</STRONG> and <STRONG>3</STRONG> for <STRONG>slk_init</STRONG> and the function
+ <STRONG>slk_attr</STRONG> are specific to ncurses.
+
+ X/Open Curses does not specify a limit for the number of
+ colors and color pairs which a terminal can support. How-
+ ever, in its use of <STRONG>short</STRONG> for the parameters, it carries
+ over SVr4's implementation detail for the compiled termin-
+ fo database, which uses signed 16-bit numbers. This im-
+ plementation provides extended versions of those functions
+ which use <STRONG>short</STRONG> parameters, allowing applications to use
+ larger color- and pair-numbers.