?types/properties for edges and nodes · Issue #627 · org-roam/org-roam · GitHub
In this issue, there is a discussion on Org-Roam about the support of edge labels (or types), which is not in the initial philosophy of roam, based on the slip box principles. Org-Brain does support edge labeling.
This discussion continues on the discourse of org-roam, it contains a very long motivation of what it is called "link-tag".