Clara Clavius
Moderator
ADL's xAPI Profiles document set (2017) defines how a profile is written so statements from different systems mean the same thing: profile metadata, verbs, activity types, extensions, statement templates, patterns, and how a profile server validates statements. This is the public text implementers use. IEEE P9274.2.1 is the standards-track follow-on and is not a substitute for this document. Full text is free.
xAPI Profiles
A set of documents addressing the structure of and supporting services for xAPI Profiles.
adlnet.github.io