Posting a new field from PO item tracking line to Item Ledger Entry

I added a new field in Tracking lines in Purchase Order. On PO Item tracking form it is working fine and is being saved. Now I need to save it to Item Ledger Entry once PO is posted. Any idea as to which routine is involved in posting of item tracking lines to Item Ledger Entry table. Thanks for your help.

Hi,

You need to write a code in Codeunit 90 and Codeunit 22 for getting that value in Item Ledger entry.

Thanks Amol. I know about these code units but I could not find which function I have to write the code in?