Representing 'current' membership/affiliation when no dates are available

[lambdamusic]

I have data about researchers and historical affiliations and I know which is the most recent affiliation (but have no dates).

What's the best pattern to represent 'current' membership without reference to dates? Here's a draft implementation..

{
    "@type": "Person",
    "familyName": "Doe",
    "givenName": "John",
    "affiliation": [
        {
            "@type": "OrganizationRole",
            "affiliation": {
                "@type": "Organization",
                "@id": "http://www.grid.ac/institutes/grid.4886.2"
            },
            "description": "Current affiliation"
        },
        {
            "@type": "Organization",
            "@id": "http://www.grid.ac/institutes/grid.421234.2"
        },
        {
            "@type": "Organization",
            "@id": "http://www.grid.ac/institutes/grid.457768.f"
        },
        {
            "@type": "Organization",
            "@id": "http://www.grid.ac/institutes/grid.457836.b"
        }
    ]
}

[RichardWallis]

See issue #7 for the context of the move from the main Schema.org issue tracker to this repository.