When setting up plan types , these can be optionally designated as "Approved Cost Budget" Or "Approved Revenue Budget" or both.
A project can have only one budget plan type that is designated as an approved cost budget or as an approved revenue budget.
These "Approved" plan types enable the applications to use the corresponding plan version for specific purposes like for example :
1. On a contract project, the system checks the project funding amount against the current baseline version of an approved revenue budget.
2. When you create a baseline version for an approved cost budget or approved revenue budget plan type on a project for which a primary cost forecast or primary revenue forecast plan type also exists, the system automatically creates an initial cost or revenue forecast version based on the corresponding approved budget version, if no forecast version exists.
3. The system uses approved budget and primary forecast plan versions as the default display versions when you view budget or forecast information using shortcuts from the Project Home page, and when you view budget or forecast information using project performance reporting features.
Reference : Oracle Project Implementation User Guide , Chapter 6, Heading : Financial Plan Types