This tab allows user ability to manage the authentication context method classes on Identify. Its purpose is for the assurance level support.
Let us also have a look at the form for adding and editing authentication context method class:
Method class: Specifies the method class. Its format must be in URI.
Comparable value: Specifies the integer value for the method class.
You can find a list of the method classes that you need to initialize for Identify here: http://msdn.microsoft.com/en-us/library/hh599318.aspx