The current alternate link is stating that there is a relation between two web resources, when in fact it is stating that there is a relation between a web resource and a representation.
This was explained in a thread:
and with diagrams here
In short the current spec is saying something that is not quite true if we consider the use we are making of the alternate link. If the id of the entry is a resource, then it is not an alternate resource, to the one pointed to, but rather the representation at hand is an alternate representation of the pointed to resource. This has the advantage of being precisely true.
Replace in section 18.104.22.168 point 1
[[ The value "alternate" signifies that the IRI in the value of the href attribute identifies an alternate version of the resource described by the containing element. ]]
[[ The value "alternate" signifies that the containing element is an alternative representation of the IRI in the value of the href attribute. ]]
none really as I think the new text expresses the intention of the group better than the old text. Literally the old text makes assertions about resources that won't always be true - especially as the diagrams illustrate if an entry is moved from one location to another (which was the whole point of allowing ids)