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Re: manunal page - uninterpretted dot

From: Werner LEMBERG
Subject: Re: manunal page - uninterpretted dot
Date: Tue, 27 Nov 2012 09:27:43 +0100 (CET)

> I believe this is the most confusing part in groff(7):
>> \.     An uninterpreted dot (period), even at start of line.
> AFAIK the dot character is just the default control character and
> has a special meaning only at the beginning of the line.  Nowhere
> else.

Yes.  However, macro expansion can make some elements vanish before
the dot.

> If the \.  sequence cannot be used to suppress the meaning of
> control character at the beginning of the line, it makes no sense to
> use this sequence at all.  Am I right?

No, see below.

> So what about removing this line from documentation at all?

Well, `\.' is even in the original troff documentation...

The very usage is not `\.' but `\\..' within a macro:

  .de foo
  .  nop foo
  .  de bar
  .    nop bar defined within foo

After macro expansion, `\\..' reduces to `\..' which simply gets
interpreted as `..', and this is exactly what's needed to define `bar'
within `foo'.  In other words, the necessity of having `\.' is not to
somehow extract a special meaning of `.' but rather to make `\' vanish
(which has been written as `\\' within the macro).


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