Question with tsearch2 (or it might be a general one too)

Hello

A newbie to PostgreSQL from MySQL and just trying to learn tsearch2. In
one of the examples at:

http://www.sai.msu.su/~megera/postgres/gist/tsearch/V2/docs/tsearch-V2-intro.html

the query given is:

SELECT intindex, strTopic FROM tblmessages
WHERE idxfti @@ to_tsquery('default', 'gettysburg &
address')
AND strMessage ~* '.*men are created equal.*';

What does the '@@' in the query means?

I did a search at:

http://search.postgresql.org/www.search?ul=http%3A%2F%2Fwww.postgresql.org%2Fdocs%2F8.1%2Finteractive%2F%25&fm=on&cs=utf-8&q=%40%40

an it dosnt return any result.

Is this specific to tsearch2? What does that mean?

Ritesh