how to check what version a file is made in

Good evening,
is there a way to check what version of Blender a file is made in? I am wanting to study Sintel's bone driven shape keys and they are all missing when I open her in 2.58.
I am unable to make bone drivers in IK chains recognize rotation.
Thanks,
Scooter

It's possible using very mucky methods which, I'll wager to say, are way too troublesome for this sort of thing. But in any case, this document provides information on the file structure of the .blend format which you can decompile and peek at.
Read the section just under "file header."
[You must be registered and logged in to see this link.]

edit, I myself have found that IPO drivers from older rigs are all missing when imported into more recent versions of Blender and I haven't been able to find any info on how one works with drivers currently.

Thanks for the reply.
That is an interesting article and I learn more every day.
By the time I was done studying Sintel, I found that I do not believe that she is set up with bone driven shape correctrion using a rotating bone. I originally got that technique from Captain Blender.
I will learn a new way.
Thanks again.
Scooter