Basic resource typing through HTTP Link header

In order to promote ad hoc discovery of information, servers practice advertising self-describing resources. One way for servers to do this is by advertising the resource type (rel=type) in HTTP Link header. Explicit types can also help to categorise resource lifecycles (for server's management) and data partitioning eg. it is somewhat integral to LDP given its interaction models. When a client encounters Web resources without context, they can at least have a basic understanding what a resource may contain provided that they meet the authorization requirements.

Some cases are listed below and certainly there are others. Should the Solid spec have a requirement (at any level / case by case) for significant types that can be encountered in the ecosystem?

• Container type (eg. ldp:Container, ldp:BasicContainer): https://github.com/solid/specification/pull/160#issuecomment-636822687 (see also https://github.com/solid/specification/pull/190 )

• LDP compatibility (eg. ldp:Resource): https://www.w3.org/TR/ldp/

• Solid resource (eg. solid:Resource): https://github.com/solid/specification/issues/194#issuecomment-694828342 explains (with some diff to ldp:Resource).

• Storage (eg. pim:Storage): https://github.com/solid/specification/issues/153#issuecomment-624630022 to help client determine root container - on way to discovering its creator/controller.

• WAC/Access-control list (eg. solid:AccessControlList): https://github.com/solid/specification/issues/105#issuecomment-551272993 to help client determine that a resource contains authorization policies. Related: https://github.com/solid/specification/issues/31

• Memento types (eg. mem:Memento, mem:OriginalResource): https://github.com/solid/specification/issues/61

• Fixed resource (eg. http://www.w3.org/2006/gen/ont#FixedResource)

• Shapes tree (eg. tree:shapeTreeResource): https://shapetrees.github.io/specification/primer

• Provenance (eg. solid:Provenance ): after via rel="http://www.w3.org/ns/prov#has_provenance": https://github.com/solid/specification/issues/177#issuecomment-623737444 where it can contain provenance record (mix of activity, entity, agent..)

• ODRL resource: (eg. http://www.w3.org/ns/odrl/2/Resource): potentially described in the formal-semantics document with the ODRL link relation type (eg. odrl:has_policy): https://github.com/w3c/odrl/issues/12

• Other partitioning: https://github.com/solid/specification/issues/105#issuecomment-552131166

• ?

Start by reviewing the linked Solid specification issues and pull requests, along with the LDP, Memento, Shape Trees, provenance, and ODRL references. Determine whether the Solid specification should require rel=type for the listed resource categories and at what level. Done requires a resolved scope and an agreed specification change, not just a list of possible resource types.