Hi rhb3
Motorola S19, S28, S37 (is that the lot - maybe there are more?) differ in the addressing range possible. If you are using a device with 64k then only 2 bytes are needed to address each location (a short pointer). Once you get above 64k then it is necessary to use three byte pointers and so on up.
There is nothing to stop you using S28 also for 64k projects - the S record will simply be slightly larger in size since there are three bytes (actually ascii hex bytes in the file format) instead of 2.
Most debuggers can handle all sorts of formats, especially ELF, which is generated by by most compilers so there is probably no reason to generate s-records for normal work. The s-records are useful when SW is distributed to be loaded by serial boot loaders and the like and for programming chips in programmers (it's a long time since I used such a device...). I think that you will find the the Codewarrior for your device will automatically recognise the format...
S-rec and Intel hex are the two, probably, most known such formats and it is also easy to convert from one to the other. If you know Intel hex then Motorola Hex is just as easy to get to know and understand.
Regards
Mark Butcher
www.mjbc.ch