Include One-Time Items in Receiving Value Report

We are 12.1.3 .We use the receiving value report to reports items lying in receiving and yet to be delivered.We also use expense POs (POs without Part#s) and the only way to make this report show expense POs received and not delivered is by entering Yes against the parameter Include One Time Items.If this is No the report only reports invenotry POs that are sitting in Receiving..

Questions:

1.What are one time items?- Are these expense items?

2.Is the purpose of this report to show expense POs also that are lying in receiving and not delivered yet?