I'm not sure I understand your question. There is no fixed list of possible masks. You can create your own mask using any of the support masking characters as listed in the documentation.

If you are referring to the list that is shown in the dropdown at design-time, then I'm not sure if that list is available at run-time. It probably comes from the UIType editor the property, which means that list is defined in the Infragistics.Win.Design assembly. It may or may not be publicly exposed, but even if it is exposed, it will be pretty difficult to get to and it won't be possible unless your users also have the Design assembly on their machines, which means they would have to have NetAdvantage installed.