EPP is an internet standard. The software we use, CoCCA, follows that standard. Here are some of the documents for it.

1. CoCCA epp fAQ
2. ICANN on EPP status codes
3. rfc5730
4. rfc5731
5. rfc5732
6. rfc5733
7. rfc5734
8. rfc8748
9. rfc3915
10. rfc5910 dnssec
11. rfc4033 dnssec
12. Why dnssec is important

We have released Zenaida an open source EPP client that people can look at or use.