Open System Services System Calls Reference Manual (G06.25+, H06.03+)

termcap(4) OSS System Calls Reference Manual
terminal.)
Tabs and Initialization
If the terminal needs to be in a special mode when running a program that uses these capabilities,
the codes to enter and exit this mode can be specified by the ti and te capabilities. This need
arises, for example, from terminals like the Concept terminal with more than one page of
memory. If the terminal has only memory-relative cursor addressing and not screen-relative cur-
sor addressing, a screen-sized window must be fixed into the display for cursor addressing to
work properly. This is also used for the Tektronix 4025 terminal, where the
ti capability sets the
command character to be the one used by termcap.
Other capabilities include is, an initialization string for the terminal, and
if, the name of a file
containing long initialization strings. These strings are expected to set the terminal into modes
consistent with the rest of the termcap description. They are printed in the following order:
• is
• setting tabs using the ct and st capabilities
• if
A pair of sequences that does a harder reset from a totally unknown state can be analogously
given as the rs and if capabilities. These strings are output by the reset program, which is used
when the terminal gets into a wedged state. Commands are normally placed in the rs and rf
capabilities only if they produce annoying effects on the screen and are not necessary when log-
ging in. For example, the command to set the DEC VT100 terminal into 80-column mode would
normally be part of the is capability, but it causes annoying behavior of the screen and is not nor-
mally needed because the terminal is usually already in 80-column mode.
If the terminal has hardware tabs, the command to advance to the next tab stop can be indicated
by the ta capability (usually ˆI). A backtab command that moves leftward to the previous tab
stop can be indicated by the bt capability. By convention, if the terminal driver modes indicate
that tab stops are being expanded by the computer rather than being sent to the terminal, applica-
tions should not use ta or bt, even if they are present, because the user might not have the tab
stops properly set. If the terminal has hardware tabs that are initially set every n positions when
the terminal is powered up, then the numeric it capability is given, indicating the number of posi-
tions between tab stops.
If there are commands to set and clear tab stops, they can be given as the ct (clear all tab stops)
capability and the st (set a tab stop in the current column of every row) capability. If a more
complex sequence is needed to set the tabs than can be described by this, the sequence can be
placed in the is or if capabilities.
Delays
Certain capabilities control padding in the terminal driver. Delays embedded in the capabilities
cr, sf, le, ff, and ta cause the appropriate delay bits to be set in the terminal driver. If the pb capa-
bility (padding baud rate) is given, these values can be ignored at baud rates below the value of
pb.
Miscellaneous
If the terminal requires other than a NULL (zero) character as a pad, this can be indicated by the
pc capability. Only the first character of the pc string is used.
If the terminal has commands to save and restore the position of the cursor, indicate this with the
sc and rc capabilities.
If the terminal has an extra status line that is not normally used by software, this fact can be indi-
cated in termcap. If the status line is viewed as an extra line below the bottom line, then the hs
capability should be given.
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