CORBA35 — Why is the enum ThreadPolicyValue completely zapped from IDL

In the text of this document the policies are described and what minimum corba supports. In the text for example it says for ThreadPolicy only ORB_CTRL_MODEL is supported, SINGLE_THREAD_MODEL not. Why is the enum ThreadPolicyValue completely zapped from IDL, why not just define this enum with one member. Makes it possible to check for this enum, according to the spec the enum should be completely zapped.