adlnet/xAPI-Spec — pull request #117 by fugu13 (2013-03-28 21:16:01+00:00)
Title: Clarify Activity language slightly

Clarify language around objectType to align with the rest of the spec & use MUST, plus rephrase around Activity ID rather than Activity URI (URI is just the data type of the ID, especially as the definition already has another URI and will soon have one more).