The AUXINFO format allows storing of the 12-character ISRC code (which is also used for CD’s), a 13-character UPC/EAN code (basically the bar code that is also used on the packaging), and the date and time of recording.
I think the recorder identification is stored in the SYSINFO data. I haven’t confirmed it yet but probably every DCC cassette contains data about the recorder that was used to create it. The first thing that happens in the DCC730/951 when it powers up is that the front panel sends a string to the digital board controller containing “PHIL-0001-NL-951/730DDU2113U032”. This is probably stored as the recorder string on every cassette that you record with it.
We don’t have the drawings that belong to the English system description but the drawings are not necessary to understand the format. As Max already mentioned, the German system description has some of the drawings that are missing (notably the one with the location and numbering of the holes in the DCC cassette) and there’s also the 3rd generation circuit description.
We currently only have datasheets for the 3rd generation chip set (and some of the earlier chips but not all). I understand that @DRDCC is in contact with someone who will provide datasheets for the earlier chipsets, so we’re working on that.
My website digitalcompactcassette.github.io has a lot more information but I admit, it could be better organized. If only I had some more time…