Put this code in After Generated Code of LOG:TaskType - is this the best place? - but it seems to work.
lb:hideemployeesysid = 1 !jvz 20110418
if INLIST(LOG:TaskType,'StaffAvailability','Incidents','StaffDevelopment','EmployeesPaymentQuery')
lb:hideemployeesysid = 0
else
lb:hideemployeesysid = 1 !jvz 20110419 not required
END
put lb:hideemployeesysid in hide field of EMP:EmplyoeeSysID