Characteristic relationship in Integrated planning

Hi Experts,

This is a general question I am posting to the forum. I tried to search for the required information on this topic, but no luck.

What is characteristic relationship in infoprovider does?

according to help.sap, I understood that, it is to check the valid combinations and secondly to derive characteristic value.

if it is input ready query, then it is clearly understood that it checks valid combination and not allow to create or change for invalid combination.

what happens if it is incase of automatic planning?

Ex: I wanted to copy the revenue of 2009 to 2010.

source record in real time is Customer(c1) custgroup(#) calyear(2009) revenue (1000)

while copying, can i derive the value of custgroup using attribute table? cust group is attribute of customer. So in the customer table, C1 is having cust group as A. in the newly copied record I should be deriving the custgroup as A instead of #.

so I defined char relation ship as attribute of   source as customer and target as customer group with derivation 

is that ok? or do I need to do some thing else for this requirement.

More over, if possible can you send some documentation on this topic. I already gone through help link but not comfortable.

http://help.sap.com/saphelp_nw70ehp2/helpdata/en/e3/e60138fede083de10000009b38f8cf/frameset.htm