Consistent handling of property terms and type terms

[multimeric]

trafficstars

It is accepted that RO-Crate does not allow URIs or CURIEs as properties. I can't find exactly where this is written in the spec, but this relates to the idea of the metadata being compacted, and crs4/rocrate-validator certainly flags such properties:

{
  "@context": [
    "https://w3id.org/ro/crate/1.2/context",
    {"ex": "https://example.org/terms#"}
  ],
  "@graph": [
    {
      "@id": "ro-crate-metadata.json",
      "@type": "CreativeWork",
      "conformsTo": {"@id": "https://w3id.org/ro/crate/1.1"},
      "about": {"@id": "./"}
    },
    {
      "@id": "./",
      "@type": "Dataset",
      "name": "Example dataset for RO-Crate specification",
      "description": "Official rainfall readings for Katoomba, NSW 2022, Australia",
      "datePublished": "2022-12-01",
      "license": "MIT",
      "ex:hasVersion": "1.0"
    }
  ]
}

       [ ro-crate-1.1_2.1 ]  Validation of the compaction format of the file descriptor:                                                                                                                                                                       
                             Check if the file descriptor is in the compacted JSON-LD format                                                                                                                                                                   
         Detected issues                                                                                                                                                                                                                                       
         - [Violation]: The 1 occurrence of the JSON-LD key "ex:hasVersion" is not allowed in the compacted format because it is not present in the @context of the document   

However, the same rules don't seem to apply to @type, despite also being an IRI:

{
  "@context": [
    "https://w3id.org/ro/crate/1.2/context",
    {"ex": "https://example.org/terms#"}
  ],
  "@graph": [
    {
      "@id": "ro-crate-metadata.json",
      "@type": "CreativeWork",
      "conformsTo": {"@id": "https://w3id.org/ro/crate/1.1"},
      "about": {"@id": "./"}
    },
    {
      "@id": "./",
      "@type": ["Dataset", "ex:Dataset"],
      "name": "Example dataset for RO-Crate specification",
      "license": "MIT",
      "description": "Official rainfall readings for Katoomba, NSW 2022, Australia",
      "datePublished": "2022-12-01"
    }
  ]
}

Gives

 [OK] RO-Crate is a valid ro-crate-1.1 !!!

I personally am a big fan of CURIEs because they let me namespace my types and properties to avoid clashes, while supporting multiple vocabularies. However if we are going to ban them in properties, I think they should also be banned in @type, for consistency.