Nyet is funny^^^
I'm not sure I understand your question. You want to know where the ECU part numbers come from? I guess you know they're printed on the outside of the ECU itself? As far as definition files go, there's plenty on here and a few damos as well, if you would like to start your own I think a few of us would be more than willing to help. Chances are, even if you find a definition file for your car, it probably won't line up. For each yr make model you have different hardware parts for different parts of the world with different software revisions, and to top that all off, old Bosch likes to take and switch it all around anyway (map locations).
Try to read your ECU with Nefmoto software. Read up on that, constant battery supply, etc. Open up WinOLS demo by EVC, and download the seat Leon damos on this site. Go through in 2d mode and have a look at the hex file. After that, it makes sense.