[Pharo-project] Image file format ?

Hi All, I'm looking for information on the image file format, something that tells me the layout. A little like this: +--------+ ! version ! +--------+ ! count ! +--------+ etc. I can glean this information from the Squeak C sources but I'm wanting some additional information for validation. Maybe it is in the blue book but I have also read that Squeak varies on this a little. Also - what is a Compact Class Array section of the image file? Rgs, James.