Hi Tamalsaha,
Well, Dgraph has the concept of edges and predicates. They are technically the same. Synonymous. The sense of predicate is the same grammatical sense (That is, any value of a node is a predicate, whether it is a connection or a value). And generally “edge” we refer abstractly to any node value as well. So we use “Vale edge” instead of simply “edge”.
Edges are generally a connection between two points (as in geometry and mathematics), but when we say “Value Edge” we are referring to a specific edge that does not create a relationship between N nodes, but stores information in a Scalar Type.
So, going back to the documentation point. It says that it is not possible to use filters that are specific to edges in node relations. You can only have the value edge as a reference for a query at the root and not within the body of the query. Because that value edge is not a relationship between nodes. Only, in that case, you can use the filter.
Cheers.