troubles around using the underscore "_

[as-muncher]

When I search on btdig say "a_b" without the quotation marks, where "a" and "b" are two separate words, but that the search term I am looking for is the one term together, joined by an underscore, btdig comes up with searches for "a" and for "b" when the "relevance" tab is selected, but doesn't show "a_b". I don't want btdig to treat the underscore as a space. If my torrent search was for "a b" then I would put the quotation marks. But I need btdig to not treat it as a space.