Re: macro returning a value?

[Peter Schaffter]

On Mon, Nov 15, 2021, Ulrich Lauther wrote:
>   .de Pos
>   \R'foo (\\n[.d]-\\n[.v]*254+1)/72000'\\n[foo]mm/10
>   ..
> 
> which allows you to enter
> 
>   position: \n[.d] units, \*[Pos].
> 

> > Wow! Works nicely.
> > 
> > And I had to add a line ".sp -1v" at the end of the  macro; otherwise I get 
> > a
> > blank line after position: ...
> > 
> 
> I now found out that the space between "foo" and the openening
> bracket causes the unintended blank line.  But why?

You shouldn't be seeing a blank line.  What's more, removing the
space before the opening parens should cause the \R escape to fail
with 'troff: <file>:<line>: warning: missing number'.  A backtrace
points directly to the \R line. 

I'm mystified.  Can you send a small example exhibiting the problem
(input and output) along with your groff command line?

-- 
Peter Schaffter
https://www.schaffter.ca