[AUCTeX] Search (and replace) throughout a document

[Philip]

Hi

Very often I need to change some notation throughout a whole document,
and I am happy to see:

http://www.gnu.org/software/auctex/manual/reftex/Multifile-Documents.html

But I can not find the answer on how to do it in the manual. I'd like to
be able both to search and to search and replace.

Thanks! Philip.