+ set_pglen_inch slengthYI Set page length to
+ #1 hundredth of an
+ inch (some implemen-
+ tations use sL for
+ termcap).
+
+ <STRONG>User-Defined</STRONG> <STRONG>Capabilities</STRONG>
+ The preceding section listed the <EM>predefined</EM> capabilities.
+ They deal with some special features for terminals no
+ longer (or possibly never) produced. Occasionally there
+ are special features of newer terminals which are awkward
+ or impossible to represent by reusing the predefined capa-
+ bilities.
+
+ <STRONG>ncurses</STRONG> addresses this limitation by allowing user-defined
+ capabilities. The <STRONG>tic</STRONG> and <STRONG>infocmp</STRONG> programs provide the <STRONG>-x</STRONG>
+ option for this purpose. When <STRONG>-x</STRONG> is set, <STRONG>tic</STRONG> treats
+ unknown capabilities as user-defined. That is, if <STRONG>tic</STRONG>
+ encounters a capability name which it does not recognize,
+ it infers its type (boolean, number or string) from the
+ syntax and makes an extended table entry for that capabil-
+ ity. The <STRONG>use_extended_names</STRONG> function makes this informa-
+ tion conditionally available to applications. The ncurses
+ library provides the data leaving most of the behavior to
+ applications:
+
+ <STRONG>o</STRONG> User-defined capability strings whose name begins with
+ "k" are treated as function keys.
+
+ <STRONG>o</STRONG> The types (boolean, number, string) determined by <STRONG>tic</STRONG>
+ can be inferred by successful calls on <STRONG>tigetflag</STRONG>, etc.
+
+ <STRONG>o</STRONG> If the capability name happens to be two characters,
+ the capability is also available through the termcap
+ interface.
+
+ While termcap is said to be extensible because it does not
+ use a predefined set of capabilities, in practice it has
+ been limited to the capabilities defined by terminfo
+ implementations. As a rule, user-defined capabilities
+ intended for use by termcap applications should be limited
+ to booleans and numbers to avoid running past the 1023
+ byte limit assumed by termcap implementations and their
+ applications. In particular, providing extended sets of
+ function keys (past the 60 numbered keys and the handful
+ of special named keys) is best done using the longer names
+ available using terminfo.