what is ledger "0004" for invest projects - pgm ZAIMCNEW

Dear,

I'm working on module Investments in release SAP 4.7.

I used program ZAIMCNEW, given by OSS note, to correct report budget.

This program created a document with ledger 0004 et 0021.

I can see the lines corresponding to ledger 0021 using transaction CJ3B, but I cannot see the lines corresponding to ledger 0004.

I would like to know what is a ledger in module IM-PS, and at what corresponds this specifical ledger "0004".

Could someone help me on this problem ?

Thank's in advance for your answer.

L.Laffond