Is there any (other) guide about how to search in the emacs-devel archives?

I am frequently trying to find some old threads, and the search
functionality usually seems to be of
no help. As the bottom of the archives page (
https://lists.gnu.org/archive/html/emacs-devel/) tells
me that the search functionality is powered by `Namazu`, I have tried to
find in its docs how to use
it. It says that using a space in a query, by default, does the same as the
AND operator (see
http://www.namazu.org/doc/manual.html#query). However, when testing it, I
have found that that is
not the case (also the and operator does not work).

Wouldn't it be a good idea to add some info about how to use the search
functionality?