As I understand it, the link rel="alternate" is an alternate representation of the current entry - which is a comment about a resource.
The resource itself is identified in the link rel="related". Links which are related to this item are also listed with a link rel="related". How is the URI being discussed to be identified when there are multiple links of rel="related"?
The link rel="related" has two uses: 1.) To identify the resource being commented on. 2.) To identify related resources to the resource being commented on.
Thanks Mike.