The tag wiki for relationships says, "Relationship is a module used for relating entities." However, the Relationship module has been abandoned. While there is a new Relation module for D7, most of the tags in this section appear to be about Relationships in Views.
Is it possible to rename tags? I would propose a separate tag for the Relations module and a views-relationships tag (similar to the existing views-filter, views-handler) so that there is less ambiguity.