RE: [Groff] [Tbl]Controlling line thickness in tbl

[Ted Harding]

> On 29-Dec-03 George, Russell A wrote:
> My understanding from the troff tutorial is that 3000u
> would be 1500 points or about 20.8 inches assuming a
> vertical resolution  of about 1/2 point. I assume the
> vertical resolution is the limitation here since the
> thickness of a horizontal line is the issue.
> 
> Russell George.

This is a misapprehension. In groff, with PostScript output
("-Tps", the default), 1000u = 1 point (1/72 inches), so
3000u = 3/72 = 1/24 inches.

Hence the solution I gave earlier:

>> \X'ps: exec 0 setlinecap'
>> .TS
>> tab(#);
>> c c c c.
>> _
>> a#b#c#d
>> _
>> a#b#c#d\D't 3000u'\h'-3000u'
>> a#b#c#d
>> _
>> a#b#c#d\D't 100u'\h'-100u'
>> _
>> a#b#c#d
>> _
>> a#b#c#d
>> _
>> .TE

will generate 2 horizontal lines with tbl's default line
thickness, 1 line with thickness 3 points, and 3 lines
with thickness 0.1 point.

Other devices have other resolutions. You could use
a device-independent resolution:

  \D't 3p'\h'-3p'

for 3-point thickness. (By the way, the presence of
the \h'-3p' here, and similar elsewhere, is due to the
fact that \D't <n><unit>' generates a horizontal motion
of amount <n><unit>s; illogical, but there it is.
The \h'-<n><unit>' undoes this.)

Ted.

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Date: 03-Dec-01                                       Time: 17:50:02
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