properties.txt

https://groups.google.com/g/gremlin-users/c/6EXYq2Howdo/m/hST6BW97AgAJ

The reason properties on properties makes sense for vertices and not for
edges is rooted in database design and not logical semantics.
A property on a vertex is a record as is an edge in the database sense.
Hence, we have use cases where we want to know who added a property on a
vertex (as a record).
For edges, the property on the edge is not a record and thinking about it
as such would make the data model really complex (because you could then
get recursively more complex). Hence, all properties of the edge are part
of the same record