>> Sorry, I don't understand. Do we in general distinguish nil from the empty list in documentation?
> 
> I don't know.  I thought the reader might not be aware of their
> equivalence, so being explicit would be better.
> 
>> Or did you mean that the phrase should be "If STRINGS is the empty list..."?
> 
> Yes, that would take care of the issue.

Now done in the doc string and in searching.texi.

New patch attached.