IMHO, the use of + and - days makes the system a little more complicated, as does having data from two different days in one XML file. If I were making the listings (which i'm not, and thanks _very_ much for providing them :-), i'd only include midnight-midnight listings in each file and allow retrieval by date rather than +/- days.You did see that the xmltv project mandates that all the data is in one file though?
I don't know about xmltv but i'm not arguing against having all the data in one file. If done correctly, that could work. It's just confusing to have a file identified by one date which contains programmes for only 3/4s of that day and 1/4 of the following day!
I know what you are saying, but "complex" is actually dependent on what you want to do with the data I think. For many uses a single file per day will help, but for others a single file with everything is what we want.
If the file's structured correctly, then it doesn't matter too much if the data is in separate files or all in the same one - the tree-like structure of XML makes it a breeze to work with either way.
Cheers, Holden