32 bit ECU multiple maps?

[Hawk296]

While looking at multiple 32 bit ROMs in ecuedit, there are things such as Desired Boost A, B,C,D etc. Using xmlwrite to make the definitions, the 2005 sti (A2ZJB10J)has all 4 of these the same but things like the 2006 wrx (A8DH200X) image and my baja turbo image (A2WC501L) only D works for these maps. What is the reason for these multiple maps? Are they all supposed to have 4 maps but the offsets are incorrect on some?

....Also....
Whats up with the negative ignition timing on some of these. That makes no sense to me.

[ECUPancakes]

I would also like to know this.