groff: Page Layout
5.15 Page Layout
================
'gtroff' provides some very primitive operations for controlling page
layout.
-- Request: .pl [length]
-- Request: .pl +length
-- Request: .pl -length
-- Register: \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 number register
'.p'.
Note that this only specifies the size of the page, not the top and
bottom margins. Those are not set by 'gtroff' directly. ⇒
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.
'gtroff' provides several operations that help in setting up top and
bottom titles (or headers and footers).
-- Request: .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).
Without argument, 'tl' is ignored.
Some notes:
* The line length set by the 'll' request is not honoured by
'tl'; use the 'lt' request (described below) instead, to
control line length for text set by 'tl'.
* A title line is not restricted to the top or bottom of a page.
* 'tl' prints the title line immediately, ignoring a partially
filled line (which stays untouched).
* It is not an error to omit closing delimiters. For example,
'.tl /foo' is equivalent to '.tl /foo///': It prints a title
line with the left justified word 'foo'; the centered and
right justified parts are empty.
* 'tl' accepts the same parameter delimiting characters as the
'\A' escape; see ⇒Escapes.
-- Request: .lt [length]
-- Request: .lt +length
-- Request: .lt -length
-- Register: \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 of type '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 of this is available in the '.lt' read-only
number register; it is associated with the current environment
(⇒Environments).
-- Request: .pn page
-- Request: .pn +page
-- Request: .pn -page
-- Register: \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 number 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.
-- Request: .pc [char]
Change the page number character (used by the 'tl' request) to a
different character. With no argument, this mechanism is disabled.
Note that this doesn't affect the number register '%'.
⇒Traps.