I can't explain much. All I know is that if you change the duration parameter it will change the length of the IR transmission for that particular key. Sometimes people will have trouble with their equipment not responding to the neo every time. If you find yourself having to press buttons several times before your DVD player responds it might be a transmission length issue. By increasing the duration many users have found their equipment now responds properly to a single press.

I don't know what the numbers represent, but from what I've read, increasing the second digit increases the transmission length. I think the default is (0;0) and I've seen users have success with (0;30). The best solution is to try different numbers. If there is a particular code that gives you problems try starting with (0;15) and see if that helps. If not, increase it until it does. Then change the duration for any other keys you have trouble with.

When you experience code reception problems in a macro, keep in mind that sometimes a DELAY between commands may solve the problem as well.