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. Note: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 which 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:
* 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 justfied parts are empty.
* Any modifications to the current environment within `tl' (e.g.
changing the font or font size) are undone after processing
`tl'.
* `tl' accepts the same parameter delimiting characters as the
`\A' escape; see Note: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
(Note: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.
- Register: \n[%]
A read-write register holding the current page number.
- 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 `%'.
Note:Traps.