There is no list other then the 1040X instructions page 5 - it is any other special circumstance that you might have that is not on the list. Only you know what your special circumstance is. (One common special circumstance is if you can be a dependent and you claimed yourself - there is no form to amend to report that, it can only be entered as a special circumstance as the reason for amending.)
https://www.irs.gov/pub/irs-pdf/i1040x.pdf
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
