R03B4201B "As Of "Processing Option in 9.1

Hi Community

Does anyone know horw the AS date processing Option on the Open AR reports work e.g the R03B4201B. e.g in AP you build a workfile for the As Of reports but this does not exist for the AR reports. Is the As Of Functionality automatically triggered when this date is populated? And, is it true As Of reporting 

THis is the description on the help screen. Has anyone used this and have a point of view.

thank you

Use this processing option to specify the "as of" date when you must produce a report "as of" a specific date. A common mistake is to use this date as the aging date, which dramatically increases report processing time.