Gear Combination (lowest
The standard way to describe a cassette is to give the smallest cog, then a dash and the largest cog. Eg: 11-32. The largest cog gives you your lowest gear. Many models come with three or four options for the combination. Eg: 11-30T (bQ), 12-25T, 13-25T, 14-25T Since we are primarily interested in touring and commuting, I usually list the combination with the lowest gear.
Another issue is that some combinations seem to be very hard to get. eg: I've had trouble finding a store that has HG50 with the 34 tooth. Chain Reaction shows if they have it in stock.