The Account Code lookup is used to create an account code mask.
Create an account code mask:
In the FND-FNC-OBJ.SOBJ-ORG-PROGRAM field, type the significant digits for the account code components you want to select. Leave Xs for the account code components that are to be ignored.
Click OK to display the selected account codes in the field/parameter on the report page.
Click Cancel to return to the report parameter page without any selections.