Field help (CPTREFLIB) 

This is the ledger on which postings are passed. This ledger is not enterable.
When a company is specified, it comes from the setup carried out at the Contexts level, for the selected depreciation plan.
If no company is entered, it is loaded by default with the ledgerIAS when the selected source depreciation plan is the IAS plan, with the Social ledger when the selected plan is any other plan.