The label "application/ipp" was meant to denote that this entity
body was to be handled by an IPP application. Which is the reason
for using the media type "application" and the subtype "ipp".
Whether or not we are using the MIME type according to the strict
definition for using a particular media type may be in question,
but the rationale is sound and it just seemed like a good fit;
i.e., we wanted this entity type to be processed by an "application"
that knows about "ipp".