Splitting FUs

Hi all,

could anybody clarify how should happen FU split and what we have as result after split:

- old FU keeps its number and new FU has been created with new number

- or completely new FUs have been created with new numbers and old one either deleted or canceled

In this regard it's unclear in help (see picture) how it works:

http://help.sap.com/saphelp_tm81/helpdata/en/4e/25aefb6f90457a8521f24dcafb6c13/content.htm?frameset=/en/61/db6f2e545f48a398fbda0698c06039/frameset.htm

Thanks in advance,

Vladimir