HI Rigga
So I was right in saying that you older guys really do have a wealth of data having seen the evolution. You personally seem to be very familiar with the military system too. For new entrants, it is easy enough to get accustomed to the current ways, but sometimes it is really useful to understand the background history. Although I work in Defence, I am only accustomed with the civilian way and only just now getting to grips with the military way (after a stint at the MAA).
I would be delighted if you would enlighten me as to why it is Part-M and not a number. I have looked around many times and asked many times but I could never get an answer. I also looked around many times and asked about 66, 147 and 145 (which I know were JARs before, but why the number) and again no answer, the only thing I eventually came up with through my own digging around was that these numbers seem to match the equivalent US 14 Code of Federal Regulations (14 CFR) numbers and for the sake of harmonisation with the US, were adopted with the JARs.
I would be grateful for your input.