You use number series relationships to select alternative number series to the ones specified for the relevant transaction or information window in the Setup (such as Sales & Receivables Setup) window.
Before you can use number series relationships, you must set up the appropriate number series in the Number Series window and you must enter it in the relevant Setup window. You must also have created relationships between the desired number series codes.
Click the AssistButton 
in the No. field on the empty document or
card. The No. Series window appears and
displays the related number series codes.
Select the number series to use by clicking the appropriate line.
Click OK to have the program insert the next number from the number series.
If you press
Enter instead of clicking the
AssistButton , the program will insert the
next number from the number series that was used the last time.