[net.text] bug using doublebox in tbl with ditroff

naftoli@aecom.UUCP (Robert N. Berlinger) (07/12/85)

Does anybody know of a bug in ditroff which causes the box 
produced by the doublebox option of tbl not to line up properly?  
The boxes don't quite come into agreement at the edges.  I'm 
working with a QMS 800 and QUICroff software.  I have contacted 
QMS and they seem to think (and I agree at first glance) that 
ditroff is probably at fault.  Anyone who could give me a lead 
would be greatly appreciated.  Thanks...  
-- 
Robert Berlinger
...{philabs,cucard,pegasus,ihnp4,rocky2}!aecom!naftoli

jaap@mcvax.UUCP (Jaap Akkerhuis) (07/15/85)

In article <1793@aecom.UUCP> naftoli@aecom.UUCP (Robert N. Berlinger) writes:
 > Does anybody know of a bug in ditroff which causes the box 
 > produced by the doublebox option of tbl not to line up properly?  
 > The boxes don't quite come into agreement at the edges.  I'm 
 > working with a QMS 800 and QUICroff software.  I have contacted 

No, it has nothing to do with ditroff. Tbl does a lot of work trying
to get the boxes to line up. It sets registers etc. to get things
lined up properly. But, since tbl has been written originally for the
C/A/T-4, all the adjustments are done for the characters on that
machine and if the characters on your output device don't have the
same characteristics as the one used on the C/A/T, the adjustments
will fail. The effect is stronger when using double lines, (so using
doublebox, || or =).

 > QMS and they seem to think (and I agree at first glance) that 
 > ditroff is probably at fault.  Anyone who could give me a lead 
 > would be greatly appreciated.  Thanks...  

You should dive into tbl (or kick QMS in doing in) and make the
appropriate changes in tbl (or add a -T flag what I ended up doing).

	jaap (mcvax!jaap)

jeff@mcnc.UUCP (Jeffrey Copeland) (07/17/85)

Your problem with tbl and ditroff sounds more like the line drawing 
characters aren't tuned correctly.  The four characters, em, rn, ul,
and ru should all meet at their ends, so horizontal lines can be drawn.
The vertical character br should meet the rn on the top and the ul on
the bottom.  ul should run under the baseline; ru at the baseline.
If the characters are tuned properly, the "smallest possible constructed
box", \(br\z\(rn\(ul\(br (see Troff User's Man, sect 12.2) will have 
corners that match.