How to get the Assignment User Status in Fast Formula?

The FF User Guide says:

GET_ASSIGNMENT_STATUS(date)

This function determine the assignment status at a given date. It populates the globals

ASSIGNMENT_EFFECTIVE_SD, ASSIGNMENT_EFFECTIVE_ED and

ASSIGNMENT_SYSTEM_STATUS. It returns 0 if successful, and otherwise error.

Example:

ERROR = GET_ASSIGNMENT_STATUS('01-JAN-1999'(date))

It appears that this function only set the assignment system status.

How can we get the assignment user status then in FF?

Thanks

James