How do you insert an Appendix into tia ditamap?

Good afternoon, one of our users is trying to insert an appendix into a ditamap that is using TIA. When they press enter to access the markup allowed window, appendix is not listed there. It was there in SMA. Is there an easy solution to this issue? Currently we are inserting a Division and giving it a navtitle of appendix, but this way it is being given a chapter number which is not desirable.

Thanks,

Bryon