# $comment
This is a graph edge type used in Stencila for representing provenance,
reactivity and other graphs.

Edge direction is always from `source` to `target`. For resource-flow edges,
this is usually from upstream dependency to downstream dependant. For
discourse edges, this is the authored relation direction. Both endpoints
reference `GraphNode.id` values.

# properties.type.$comment
This is a special property analogous to JSON-LD's `@type` keyword.

# properties.id.$comment
This is a special property analogous to JSON-LD's `@id` keyword.

# properties.kind.description
The kind of relationship represented by this edge.

# properties.actions.description
Concrete activities associated with the edge.

# properties.actions.$comment
Use this for real operations that produced or transformed the target from
the source, such as a recorded code execution or an explicit conversion.
Do not use it for static analysis relationships, inferred links, or
observed filesystem state; those belong in `evidence` and resource
metadata such as `dateCreated` and `dateModified`.