Can anybody here point me to some documentation on the Squeak/Cog/Pharo etc image file format? "read the source" is pretty useless when the source is scattered

Can anybody here point me to some documentation on the Squeak/Cog/Pharo etc image file format? "read the source" is pretty useless when the source is scattered around various Monticello repositories, which never seem to work for me thanks to the Smalltalk community's epic linkrot.