The instruction for Schedule D form seems a bit ambiguous. On line 17 it says, If both line 15(total long term) and line 16(total long term + short term) are gains, go to line 18(which makes you do the 28% rate gain worksheet). But it doesn't say what to do when you have no long term gains or losses, i.e., no transaction in your 1099-B that can be classified as long term transaction. Should I consider a blank line 15(total long term) as gain or loss?
A gain here means a positive amount, so if you have no long-term transactions you would answer no on line 17. The purpose of the question is to determine whether you may qualify for the lower tax rate on long-term gains.