GNU troff
provides some primitive operations for controlling page
layout.
.pl
[length] ¶.pl
+
length ¶.pl
-
length ¶\n[.p]
¶Set the page length to length (or increment or decrement the current value by length). This is the length of the physical output page. The default scaling indicator is ‘v’.
The current setting can be found in the read-only register ‘.p’.
This specifies only the size of the page, not the top and bottom
margins. Those are not set by GNU troff
directly. See Traps,
for further information on how to do this.
Negative pl
values are possible also, but not very useful: no
trap is sprung, and each line is output on a single page (thus
suppressing all vertical spacing).
If no argument or an invalid argument is given, pl
sets the page
length to 11i.
GNU troff
provides several operations that help in setting up top
and bottom titles (also known as headers and footers).
.tl
'
left'
center'
right'
¶Print a title line. It consists of three parts: a left-justified
portion, a centered portion, and a right-justified portion. The
argument separator ‘'’ can be replaced with any character not
occurring in the title line. The ‘%’ character is replaced with
the current page number. This character can be changed with the
pc
request (see below). The delimiter need not be a neutral
apostrophe: tl
accepts the same delimiters as most escape
sequences; see Delimiters. Without an argument, tl
is
ignored.
ll
request is not honoured by
tl
; use the lt
request (described below) instead, to
control line length for text set by tl
.
tl
prints the title line immediately, ignoring a partially
collected line (which stays untouched).
.lt
[length] ¶.lt
+
length ¶.lt
-
length ¶\n[.lt]
¶The title line is printed using its own line length, which is specified
(or incremented or decremented) with the lt
request. Initially,
the title line length is set to 6.5i. If a negative line length
is specified (which is not allowed), gtroff
emits a warning in
category ‘range’ and sets the title line length to zero. The
default scaling indicator is ‘m’. If lt
is called without
an argument, the title length is reset to the previous value before the
last call to lt
. The current setting is available in the
.lt
read-only register; it is associated with the environment
(see Environments).
.pn
page ¶.pn
+
page ¶.pn
-
page ¶\n[.pn]
¶Change (increase or decrease) the page number of the next page. The only argument is the page number; the request is ignored without a parameter.
The read-only register .pn
contains the number of the next page:
either the value set by a pn
request, or the number of the
current page plus 1.
.pc
[char] ¶Change the page number character (used by the tl
request) to a
different character. With no argument, this mechanism is disabled.
This doesn’t affect the register %
.
See Traps.