Take account.dat, stash as an example. the way how it has done is easy. Just change the quantity of one item from 127(7f, 1 byte) to 128(8001, 2 bytes), and compare those two saves. Pay close attention to those values that have been added one in value.
Same method, you will be able to map the whole file out.
This image only shows the first item in the stash. You can see the second item (E701=bytes length value) starts after the first item block which is surrounded by green line. The ones labeled stash are responsible for the whole stash, otherwise item itself. So if you want to change one of items in your stash, you need to change corresponding item blocks and the whole stash byte count values. For the value, you have to check this thread. http://www.360haven.com/forums/threa...earch-project/
Have fun guys!