Re: [Groff] condition: OR of two string comparisons

[Carsten Kunze]

> Having `.if x' instead of a new keyword `.ifx' is appealing to me.

Ok, sounds interesting.  Could also be used for .nr:

.nr <regname> x <expression>

> Assuming that we have a global register to activate a novel
> interpretation of expressions (as suggested by Colin), we could indeed
> simply stay with the currently available keywords.

But then the whole document has to be in the new syntax?  That is ok for new 
documents, but what if one just one wants to add something using the new 
extression syntax?
(Anyway that new register does not hurt if it is additional.  But it may have 
advantages to decide per request which expression syntax is used.)

> Note, however, that it gets tricky if groff tries to execute `modern'
> macros in compatibility mode (.cp 0), cf. `.de1' and friends.

Would it not be correct to switch off the extended expressions in compatibility 
mode?  So there should be no clashes.

Carsten