.MH "Headings, Footings and Titles"
.#
.SH "Three Part Titles"
A three part title is a line of output consisting of three
segments.  The first segment is left-justified, the second
is centered between the left and right margins, and the third
is right-justified. For example
.be
.lt -20
.tl `left part`center part`right part`
.lt +20
.ee
is a three part title whose first segment is "left part", whose
second segment is "center part", and whose third segment is
"right part".
.pp
.ne 5
To generate a title at the current position on the page, the
'title' command is available:
.be
 [bf .tl] /left part/center part/right part/
.ee
In fact, this  command was used to generate the previous
example.  The parameter to the title command is made up of
the text of the three parts, with each segment enclosed within
a pair of delimiter characters.  Here, the delimiter is
a slash, but any other character may be used as long as it is
used consistently within the same command.  If
one or more segments are to be omitted,
indicate this with two adjacent
delimiters at the desired position. Thus,
.be
 [bf .tl] ///Page 1/
.ee
specifies only the third segment and would produce something
like this:
.be
.lt -20
.tl ///Page 1/
.lt +20
.ee
It is not necessary to include the trailing delimiters.
.pp
To facilitate page numbering, you may include the sharp
character ("#") anywhere in the text of the title; when the
command is actually performed, 'fmt' will replace all
occurrences of the "#" with the current page number.
To produce a literal sharp character in the title,
it should be preceded by an "@@"
.be
 @@#
.ee
so that it loses its special meaning.
.pp
The first segment of a title always starts at the left margin
as specified by the [bf lm] command.
While the third segment normally ends at the right margin
as specified by the [bf rm]
command, this can be changed with the 'length-of-title' command:
.be
 [bf .lt] [cu +]N
.ee
which changes the length of subsequent titles to [cu +]N,
still
.nh
beginning
.hy
at the left margin.
Note that the title length is automatically set by the [bf lm] and
[bf rm] commands to coincide with the distance between the left and
right margins.
.#
.SH "Page Headings and Footings"
The most common uses for three part titles are page headings and
footings. The header and footer lines are initially blank.
Either one or both may be set at any
time, without a break, by using the 'header' command
.be
 [bf .he] /left/center/right/
.ee
to set the page heading, and the 'footer' command
.be
 [bf .fo] /left/center/right/
.ee
to set the page footing.
The change will become manifest the next time the top or the bottom
of a page is reached.  As with the [bf tl]
command, the "#" may be used to access the current page number.
.pp
It is often desirable when producing text to be printed on both
sides of a page to have different headings and footings on odd-
and even-numbered pages.  Although the [bf he] and [bf fo]
commands affect the headings and footings on all pages, it is possible
to set up independent headings and footings for odd- and
even-numbered pages.  For odd-numbered pages, the 'odd-header' and
'odd-footer' commands are available:
.be
 [bf .oh] /left/center/right/
 [bf .of] /left/center/right/
.ee
while the 'even-header' and 'even-footer' commands are provided for
even-numbered pages:
.be
 [bf .eh] /left/center/right/
 [bf .ef] /left/center/right/
.ee
As an illustration, the following commands were used to generate
the page headings and footings for this guide:
.be 3
 [bf .eh] /Text Formatter User's Guide///
 [bf .oh] ///Text Formatter User's Guide/
 [bf .fo] //- # -//
.ee
.#
.BT 26 "Summary - Headings, Footings and Titles"
?RQ  ".ef /l/c/r/"  blank  blank  no
Set even-numbered page footing.
?RQ  ".eh /l/c/r/"  blank  blank  no
Set even-numbered page heading.
?RQ  ".fo /l/c/r/"  blank  blank  no
Set running page footing.
?RQ  ".he /l/c/r/"  blank  blank  no
Set running page heading.
?RQ  ".lt [cu +]N"  N=60  N=60  no
Set length of header, footer and titles.
?RQ  ".of /l/c/r/"  blank  blank  no
Set odd-numbered page footing.
?RQ  ".oh /l/c/r/"  blank  blank  no
Set odd-numbered page heading.
?RQ  ".tl /l/c/r/"  blank  blank  yes
Generate a three part title.
?ET
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