- <STRONG>o</STRONG> That is, there are two standards for <STRONG>tput</STRONG>: POSIX (a subset) and
- X/Open Curses (the full implementation). POSIX documents a subset
- to avoid the complication of including X/Open Curses and the termi-
- nal capabilities database.
+ <STRONG>o</STRONG> That is, there are two standards for <STRONG>tput</STRONG>: POSIX (a subset) and
+ X/Open Curses (the full implementation). POSIX documents a subset
+ to avoid the complication of including X/Open Curses and the
+ terminal capabilities database.
+
+ <STRONG>o</STRONG> While it is certainly possible to write a <STRONG>tput</STRONG> program without
+ using curses, none of the systems which have a curses
+ implementation provide a <STRONG>tput</STRONG> utility which does not provide the
+ <EM>capname</EM> feature.
+
+ X/Open Curses Issue 7 (2009) is the first version to document
+ utilities. However that part of X/Open Curses does not follow existing
+ practice (i.e., Unix features documented in SVID 3):
+
+ <STRONG>o</STRONG> It assigns exit code 4 to "invalid operand", which may be the same
+ as <EM>unknown</EM> <EM>capability</EM>. For instance, the source code for Solaris'
+ xcurses uses the term "invalid" in this case.
+
+ <STRONG>o</STRONG> It assigns exit code 255 to a numeric variable that is not
+ specified in the terminfo database. That likely is a documentation
+ error, confusing the <STRONG>-1</STRONG> written to the standard output for an
+ absent or cancelled numeric value versus an (unsigned) exit code.
+
+ The various Unix systems (AIX, HPUX, Solaris) use the same exit-codes
+ as ncurses.