Subtotal and routine list in MM Schema

Hi Friends,

Could you please share the Std functionality of MM schema

1. Subtotal("",1,2,3,4 etc)
2. Requirement(2,3 etc...)
3. CAl Type (2,3 etc...)
4. BAse type (2,3 etc...)

i know its not possible to list the functionality of all . I only onl the most important one.

like say - Bas type 362 is given against Gross amount in MM Schema . Reason : 363 Bas type will fetch the net PO value to tax pricing . now Tax base price is this ( freight is not considered)

like wise i want to know the relevance of the above and important items in it.

Say subtotal - what it do and main items in it and its usage say 2,6, 9, 12 and its usage.

regards

manu