I've seen these values you're talking about. They look like they're part of the inventory, but they're not assigned to valid spots in it.
I don't think it's for the blocks in the world. Those would be in the chunks.dat file.
My best guess is that it's a list of all inventory items that aren't infinite. Any "unofficial" blocks that are hacked in are always infinite by default. It's the limited stacks that seem to be getting special treatment in the code, and I think that is what those data values are.
(Just something I posted in the PE section a little while ago. The forums were acting slow, so I copied my post in case it got eaten up by a 403 error.)
Could i help you with making one of the maps? i DO have epic building abilities:
These are just pics of some thing i made
Epic House stuff
Corridor of my Epic House
i didnt understand redstone untill now.
Front of my awesome house
Secret Fountain of youth and Pain
The farm our back
Pig farm inside!
What some of the Redstone connects to; a Shower and a Toilet.
The point of those 2 spoilers was NOT to advertise, but to show my epic building skills.