# description
The kind of evidence supporting a graph edge.

# $comment
This enumeration classifies how a graph edge was learned or justified.
Variants describe the evidence source or acquisition method, not the graph
relationship itself. This keeps evidence orthogonal to `GraphEdgeKind`, and
allows a single edge to carry several signals, for example an authored
declaration that was also resolved to a concrete local file.

Use `Observed` narrowly for direct inspection of existing state, such as a
filesystem entry or runtime access. Use `StaticAnalysis` for relationships
found by parsing or scanning source/configuration text without executing it.

# 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.identifiers.description
Any kind of identifier for any kind of Thing.

# properties.identifiers.$comment
Some identifiers have specific properties e.g the `issn` property for
the `Periodical` type. These should be used in preference to this
property which is intended for identifiers that do not yet have a
specific property. Identifiers can be represented as strings, but
using a `PropertyValue` will usually be better because it allows
for `propertyID` (i.e. the type of identifier).

# anyOf[].description
Evidence from an explicit authored or schema field declaration, such as a link target, citation target, include source, or media URL.

# anyOf[].description
Evidence from deterministically resolving a declared locator to a concrete graph node.

# anyOf[].description
Evidence from direct inspection of existing local state or runtime behavior, such as filesystem entries, symlink targets, or runtime reads and writes.

# anyOf[].description
Evidence from a deterministic Stencila operation, such as walking document structure, decoding a file, or materializing recorded execution outputs.

# anyOf[].description
Evidence from persisted Stencila metadata already recorded on a node, such as execution dependencies, execution digests, or execution status.

# anyOf[].description
Evidence from analyzing code, configuration, or environment files without executing them, preferably with a source location when available.

# anyOf[].description
Evidence imported from an external metadata source, service, graph, or document format.

# anyOf[].description
Evidence from a signed, cryptographic, or otherwise verifiable attestation such as a content credential.

# anyOf[].description
Evidence from a heuristic or probabilistic inference that has not been directly resolved, observed, or attested.