groff: Line Layout
5.13 Line Layout
================
The following drawing shows the dimensions that 'gtroff' uses for
placing a line of output onto the page. They are labeled with the
request that manipulates each dimension.
-->| in |<--
|<-----------ll------------>|
+----+----+----------------------+----+
| : : : |
+----+----+----------------------+----+
-->| po |<--
|<--------paper width---------------->|
These dimensions are:
'po'
"Page offset" - this is the leftmost position of text on the final
output, defining the "left margin".
'in'
"Indentation" - this is the distance from the left margin where
text is printed.
'll'
"Line length" - this is the distance from the left margin to right
margin.
A simple demonstration:
.ll 3i
This is text without indentation.
The line length has been set to 3\~inch.
.in +.5i
.ll -.5i
Now the left and right margins are both increased.
.in
.ll
Calling .in and .ll without parameters restore
the previous values.
Result:
This is text without indenta-
tion. The line length has
been set to 3 inch.
Now the left and
right margins are
both increased.
Calling .in and .ll without
parameters restore the previ-
ous values.
-- Request: .po [offset]
-- Request: .po +offset
-- Request: .po -offset
-- Register: \n[.o]
Set horizontal page offset to OFFSET (or increment or decrement the
current value by OFFSET). Note that this request does not cause a
break, so changing the page offset in the middle of text being
filled may not yield the expected result. The initial value is 1i.
For TTY output devices, it is set to 0 in the startup file
'troffrc'; the default scaling indicator is 'm' (and not 'v' as
incorrectly documented in the original UNIX troff manual).
The current page offset can be found in the read-only number
register '.o'.
If 'po' is called without an argument, the page offset is reset to
the previous value before the last call to 'po'.
.po 3i
\n[.o]
=> 720
.po -1i
\n[.o]
=> 480
.po
\n[.o]
=> 720
-- Request: .in [indent]
-- Request: .in +indent
-- Request: .in -indent
-- Register: \n[.i]
Set indentation to INDENT (or increment or decrement the current
value by INDENT). This request causes a break. Initially, there
is no indentation.
If 'in' is called without an argument, the indentation is reset to
the previous value before the last call to 'in'. The default
scaling indicator is 'm'.
The indentation is associated with the current environment (
Environments).
If a negative indentation value is specified (which is not
allowed), 'gtroff' emits a warning of type 'range' and sets the
indentation to zero.
The effect of 'in' is delayed until a partially collected line (if
it exists) is output. A temporary indentation value is reset to
zero also.
The current indentation (as set by 'in') can be found in the
read-only number register '.i'.
-- Request: .ti offset
-- Request: .ti +offset
-- Request: .ti -offset
-- Register: \n[.in]
Temporarily indent the next output line by OFFSET. If an increment
or decrement value is specified, adjust the temporary indentation
relative to the value set by the 'in' request.
This request causes a break; its value is associated with the
current environment (Environments). The default scaling
indicator is 'm'. A call of 'ti' without an argument is ignored.
If the total indentation value is negative (which is not allowed),
'gtroff' emits a warning of type 'range' and sets the temporary
indentation to zero. 'Total indentation' is either OFFSET if
specified as an absolute value, or the temporary plus normal
indentation, if OFFSET is given as a relative value.
The effect of 'ti' is delayed until a partially collected line (if
it exists) is output.
The read-only number register '.in' is the indentation that applies
to the current output line.
The difference between '.i' and '.in' is that the latter takes into
account whether a partially collected line still uses the old
indentation value or a temporary indentation value is active.
-- Request: .ll [length]
-- Request: .ll +length
-- Request: .ll -length
-- Register: \n[.l]
-- Register: \n[.ll]
Set the line length to LENGTH (or increment or decrement the
current value by LENGTH). Initially, the line length is set to
6.5i. The effect of 'll' is delayed until a partially collected
line (if it exists) is output. The default scaling indicator is
'm'.
If 'll' is called without an argument, the line length is reset to
the previous value before the last call to 'll'. If a negative
line length is specified (which is not allowed), 'gtroff' emits a
warning of type 'range' and sets the line length to zero.
The line length is associated with the current environment (
Environments).
The current line length (as set by 'll') can be found in the
read-only number register '.l'. The read-only number register
'.ll' is the line length that applies to the current output line.
Similar 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 old line length value.
Info Catalog
groff: Troff and Nroff Mode
groff: gtroff Reference
groff: Line Control