Question : Active Session Time Limit not on list

Using Windows Server 2003.
In a Policy, I wish to set the Active Session Limit to 9 hours. Unfortuntately, this is not on the list and it doesn't seem to accept text input.
If I go to an individual Terminal Server, open Terminal Server Configuration,I can set it to 9 hours - it accepts input.
However, I want to do it at policy level, as I have several servers. How can I change it to 9 in the policy?
Thanks

Answer : Active Session Time Limit not on list

JD, sorry, MaxSessionTime would be a value under that key, not a key itself.