Whenever you want to dig in deep into a MP, this is a blog to reckon with: System Center Core. It contains the technical documentation for all Microsoft MPs (the latest versions) and many non-Microsoft MPs, including their download links.
Whenever you want to know how a MP is constructed this is THE place to be. I’ve used this website many times but somehow forgot to share it.
A BIG word of thanks to the person/persons maintaining this awesome website.