Question: What is the minimum vocabulary requirement for a PSS (Packet-switched Streaming Service) server supporting capability exchange?
Option 1: Support for only the recommended attributes from the UAProf vocabulary.
Option 2: Support for all attributes in the UAProf vocabulary and at least one PSS component of the PSS base vocabulary.
Option 3: Support for the attributes in all four PSS components of the PSS base vocabulary.
Option 4: No mandatory vocabulary support; any attribute from either vocabulary can be chosen.
Explanation: According to the specifications, PSS servers supporting capability exchange must support the attributes in all four PSS components of the PSS base vocabulary. While support for UAProf vocabulary is advised, it's not the minimum requirement for capability exchange. Thus, ensuring all four components of the PSS base vocabulary are supported meets the mandatory criteria.