- The <STRONG>longname</STRONG> and <STRONG>-S</STRONG> options, and the parameter-substitu-
- tion features used in the <STRONG>cup</STRONG> example, are not supported
- in BSD curses or in AT&T/USL curses before SVr4.
+ This implementation of <STRONG>tput</STRONG> differs from AT&T <STRONG>tput</STRONG> in two
+ important areas:
+
+ <STRONG>o</STRONG> tput writes to the standard output. That need not be
+ a regular terminal.
+
+ The AT&T implementation's <STRONG>init</STRONG> and <STRONG>reset</STRONG> commands use
+ the <STRONG>tset</STRONG> source, which manipulates terminal modes. It
+ successively tries standard output, standard error,
+ standard input before falling back to "/dev/tty" and
+ finally just assumes a 1200Bd terminal. When updating
+ terminal modes, it ignores errors.
+
+ <STRONG>o</STRONG> AT&T <STRONG>tput</STRONG> guesses the type of its <EM>capname</EM> operands by
+ seeing if all of the characters are numeric, or not.
+
+ Most implementations which provide support for <EM>capname</EM>
+ operands use the <EM>tparm</EM> function to expand parameters
+ in it. That function expects a mixture of numeric and
+ string parameters, requiring <STRONG>tput</STRONG> to know which type
+ to use.
+
+ This implementation uses a table to determine the
+ parameter types for the standard <EM>capname</EM> operands, and
+ an internal library function to analyze nonstandard
+ <EM>capname</EM> operands.
+
+ The <STRONG>longname</STRONG> and <STRONG>-S</STRONG> options, and the parameter-substitu-
+ tion features used in the <STRONG>cup</STRONG> example, were not supported
+ in BSD curses before 4.3reno (1989) or in AT&T/USL curses
+ before SVr4 (1988).