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Disable or enable output depending on the value of num:
Disable any glyphs from being emitted to the device driver, provided
that the escape occurs at the outer level (see \O[3]
and
\O[4]
). Motion is not suppressed so effectively \O[0]
means pen up.
Enable output of glyphs, provided that the escape occurs at the outer level.
\O0
and \O1
also reset the four registers ‘opminx’,
‘opminy’, ‘opmaxx’, and ‘opmaxy’ to -1.
See Register Index. These four registers mark the top left and
bottom right hand corners of a box that encompasses all written glyphs.
For example the input text:
Hello \O[0]world \O[1]this is a test.
produces the following output:
Hello this is a test.
Provided that the escape occurs at the outer level, enable output of
glyphs and also write out to stderr
the page number and four
registers encompassing the glyphs previously written since the last call
to \O
.
Begin a nesting level. At start-up, gtroff
is at outer level.
The current level is contained within the read-only register .O
.
See Built-in Registers.
End a nesting level. The current level is contained within the
read-only register .O
. See Built-in Registers.
This escape is grohtml
specific. Provided that this escape
occurs at the outer nesting level write the filename
to
stderr
. The position of the image, P, must be specified
and must be one of l
, r
, c
, or i
(left,
right, centered, inline). filename is associated with the
production of the next inline image.
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