Many variables which are used to describe the terminal environment
are available to the programmer. They are:
current version of the screen (terminal screen).
standard screen. Most updates are usually done here.
default terminal type if type cannot be determined
use the terminal specification in \fIDef\*_term\fR as terminal,
irrelevant of real terminal type
full name of the current terminal.
number of lines on the terminal
number of columns on the terminal
error flag returned by routines on a fail.
error flag returned by routines when things go right.
which are of general usefulness:
reg storage class ``register'' (e.g., \fIreg int i;\fR\|)
bool boolean type, actually a ``char'' (e.g., \fIbool doneit;\fR\|)
TRUE boolean ``true'' flag (1).
FALSE boolean ``false'' flag (0).