Usage of <content> across multiple implementations

reported by Ugo Cei during the PlugFest in Basel in keywords, so my interpretation may be off.

Currently there are various different ways on how the implementation refer to the "enclosed" binary.
Some use the <content> element someuse various link relations, this became particularly apparent when testing
with various server implementations.
It seems that the specification could be clear about how to use <content> possibly with an example.