RADIUS supplied Idle-Timeout attribute

[TorryS]

I have two group of users that only really differ in required idle and session timeouts (no idle and 16 hour session vs. 30 minute idle and 4 hour sessions) and I'd like to be able to service them all with a single WLAN and captive portal.  I can easily differentiate them in RADIUS so returning different values from RADIUS would be the easiest way to handle it.

Does pfSense 2.1 use a RADIUS supplied Idle-Timeout value as well if the "Use RADIUS Session-Timeout attributes" option is checked?  If so, what value do I return from RADIUS for no idle timeout.  The CP config page says 'Leave this field blank for no idle timeout.'  Do I just not return an Idle-Timeout attribute for one group?  Return a value like 0 or -1?

Thanks