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The following drawing shows the dimensions that GNU troff
uses
to arrange a line of output on the page. Each dimension is labeled with
the name of the request that configures it.
-->| in |<-- |<-----------ll------------>| +----+----+----------------------+----+ | : : : | +----+----+----------------------+----+ -->| po |<-- |<--------paper width---------------->|
The dimensions are defined as follows.
po
| The page offset is the leftmost position of running text. |
in
| Indentation is the distance from the page offset at which text is set. |
ll
| Line length is the maximum extent of unindented running text. |
The page offset can be thought of as the “left margin”. The right margin is not explicitly configured; the combination of page offset and line length provides the information necessary to derive it.
.ll 3i This is text without indentation. The line length has been set to 3\~inches. .in +.5i .ll -.5i Now the left and right margins are both increased. .in .ll Calling .in and .ll without parameters restores the previous values.
⇒ This is text without indenta- ⇒ tion. The line length has ⇒ been set to 3 inches. ⇒ Now the left and ⇒ right margins are ⇒ both increased. ⇒ Calling .in and .ll without ⇒ parameters restores the previ- ⇒ ous values.
Requests exist to place line numbers and margin characters beyond the page margins; Miscellaneous.
Set page offset to offset; if offset is signed, adjust the page offset by its value. The default scaling unit is ‘m’. The default offset is 1i on typesetters and zero on terminals.
If offset is omitted, the page offset is reset to that before the
previous invocation of po
.
The page offset can be found in the read-only register ‘.o’.
This request is incorrectly documented in the AT&T
troff
manual as using a default scaling unit of ‘v’.
.po 3i \n[.o] ⇒ 720 .po -1i \n[.o] ⇒ 480 .po \n[.o] ⇒ 720
Set indentation to indent; if indent is signed, adjust the indentation by its value. The default scaling unit is ‘m’. Initially, there is no indentation. This request causes a break.
If indent is omitted, the indentation is reset to that before the
previous invocation of in
, and zero if there is none. If
indent is negative, GNU troff
emits a warning in
category ‘range’ and sets the indentation to zero; a temporary
indentation (see below) is reset to zero as well.
The effect of in
is delayed until a partially collected line (if
it exists) is output. In other words, it does not change a pending
output line’s indentation.
The indentation (as set by in
) can be found in the read-only
register ‘.i’; it ignores temporary indentation (see below). The
indentation is associated with the environment (see Environments).
Temporarily indent the next output line by offset; if offset
is signed, adjust the temporary indentation relative to the value set by
the in
request. The default scaling unit is ‘m’. This
request causes a break.
Omitting offset causes a warning in category ‘missing’.
The effect of ti
is delayed until a partially collected line (if
it exists) is output. In other words, it does not change a pending
output line’s indentation.
The read-only register .in
reports the indentation that applies
to the pending output line. The temporary indentation is associated
with the environment (see Environments).
Change (increase or decrease) the line length per the numeric expression
length. The default scaling unit is ‘m’. If not otherwise
configured (see see Paper Format), the default line length is
6.5i. If length is invalid, GNU troff
emits a
warning in category ‘number’ and ignores the request. If
length is nonpositive, GNU troff
emits a warning in
category ‘range’ and sets the line length to the device’s
horizontal motion quantum; recall Motion Quanta. The line length
is associated with the environment (see Environments). If
length is omitted, GNU troff
restores the environment’s
previous line length.
The effect of ll
is delayed until a partially collected line (if
it exists) is output. In other words, it does not change a pending
output line’s length.
The line length as set by ll
can be found in the
read-only register ‘.l’. The read-only register .ll
is the
line length that applies to the pending output line.
Similarly to .i
and .in
, the difference between .l
and .ll
is that the latter takes into account whether a partially
collected line still uses the previous length.
Next: Line Continuation, Previous: troff
and nroff
Modes, Up: GNU troff Reference [Contents][Index]