Flowspecs, filter specs, sender templates, and sender Tspecs are encoded as variable-length RAPI objects.

Every RAPI object begins with a header of type rapi_hdr_t, which contains:

• The total length of the object in bytes
• The type

An empty object consists only of a header, with type 0 and length sizeof (rapi_hdr_t).

Integrated services data structures are defined in RFC 2210, which describes the use of the RSVP with the Controlled-Load and Guaranteed services. (See Related protocol specifications for information about accessing RFCs.) RSVP defines several data objects which carry resource reservation information but are opaque to RSVP itself. The usage and data format of those objects is given in RFC 2210.