  <p>
    Activity Streams 2.0 implementations that wish to fully support extensions
    MUST support Compact URI expansion as defined by the JSON-LD specification.
    Such expansion applies to all property names as well as all property values
    explicitly defined as type <code>@id</code> in the JSON-LD @context.
  </p>

  <p>
    Over reliance on the Compact URI form can lead to ambiguity and
    interoperability issues between implementations. Therefore, Compact URI use
    SHOULD be avoided in all cas