Use of global methods in free form expression on constrained table in security policy (XDS)

Hi all,
does anyone know if it's possible to use a global method (e.g. currentWorker()) in a free form expression on a constrained table in a security policy in AX2012?

For instance, I have TSTimesheetLine as a constrained table in a security policy and I want to check if the currentWorker() equals the worker on the timesheet, so something like:
(TSTimesheetLine.Worker == currentWorker())

However, I'm getting a syntax error...


Kind regards,
Wouter