Thanks you Aubrey, this is what I was looking for
Well it is just simple:
I'have a program to catalog all ocremix mp3 (and other songs) called "Mediamonkey". It is a very usefull interface, with an access back end database. I want to put the OCRemix ID in the track number, so that I have the exact order in which the songs where released, and I can burn cds from the first mix to the last mix. It is also very usefull to search back a remix on the web site.
So I'm loading this in the database, and updating the track number with the OCR number, with the help of the xml file.