I once got a development requirement from a client that they want to change the Timesheet (CATS) approval workflow. The standard approval workflow stops if the chief position (Manager Position) assigned to an org unit is vacant. They want to change the workflow to go one level up until it finds a manager if the current org unit’s chief position is vacant. I told them it is just a configuration and you don’t have to develop or enhance anything. As always, there are lots of settings we wish that SAP would have provided as standard, but at the same time there may be some clients who don’t want to use this feature.

Solution:
Either add the following entry in the T77S0 table or enter “X” for GSVAL if there is already an entry:
GRPID: WFLOW
SEMID: VACPOS
GSVAL: X

Background on CATS Approval:
CATS approval actually uses a standard task 31000007 for approval:

Go to Default rules tab and you will find the workflow rule it uses to find approvers:

Double click the rule or use transaction PFAC to go to the rule:

This rule uses the FM to get approvers:

I came across this same situation in another implementation where, even though we maintain this entry, the workflow will still not go one level up. This was MSS HCMPF implementation and SAP did not even give an option. So I implemented custom function module just to add one extra line. I recently saw that SAP released a note to fix this and I wanted to share as this would knock one development item to develop, test, and maintain.
Note: 1579188 – HCM P&F : No agent is returned when position is vacant

Background:
HCMPF workflow uses rule 17900014 to find manager.