Darq, as I understand it, H5 means that there are only 5 seats left in fare base H. But, Q9 means that there are 9 or more seats in Q. i.e. the system will not show availability of more than 9 seats in any given class, even if more are available.

As for finding out what the codes mean, that is one of the old chestnuts of this board. If you do a search you will find many threads that partly answer your question - but there is no definitive list. Basically each airline is a little bit different...