provenance/durand_payne/1 matches the site

public static Activity Purchase_Of_Spring_By_Payne()
{
    var purchase = new Activity()
        .WithContext()
        .WithId("https://linked.art/example/provenance/durand_payne/1")
        .WithLabel("Purchase of Spring by Payne")
        .WithClassifiedAs(Aat.ProvenanceActivity);

    purchase.IdentifiedBy = [new Name("Purchase of Spring by Payne from Durand-Ruel").AsPrimaryName()];
    purchase.TimeSpan = LinkedArtTimeSpan.FromYear(1909);

    purchase.Part = [
        new Acquisition
        {
            Label = "Ownership of Spring to Payne",
            TransferredTitleOf = [
                new HumanMadeObject()
                    .WithId("https://linked.art/example/object/spring")
                    .WithLabel("Spring")
            ],
            TransferredTitleFrom = [
                new Person()
                    .WithId("https://linked.art/example/person/durand")
                    .WithLabel("Durand-Ruel Gallery")
            ],
            TransferredTitleTo = [
                new Person()
                    .WithId("https://linked.art/example/person/payne")
                    .WithLabel("Oliver Payne")
            ]
        }
    ];

    return purchase;
}

• Role shortcuts AsPrimaryName, AsAccessionNumber and AsSystemAssignedNumber each add a single classification, with the AAT terms Primary Name, Accession Number and System Number.

var activity = new Activity
{
    Context = ["https://linked.art/ns/v1/linked-art.json"],
    Id = "https://linked.art/example/provenance/durand_payne/1",
    Label = "Purchase of Spring by Payne",
    ClassifiedAs = [Aat.ProvenanceActivity],
    IdentifiedBy =
    [
        new Name("Purchase of Spring by Payne from Durand-Ruel")
        {
            ClassifiedAs = [Aat.PrimaryName],
        },
    ],
    TimeSpan = new LinkedArtTimeSpan
    {
        BeginOfTheBegin = new LinkedArtDate(1909, 1, 1),
        EndOfTheEnd = new LinkedArtDate(1909, 12, 31, 23, 59, 59),
    },
    Part =
    [
        new Acquisition
        {
            Label = "Ownership of Spring to Payne",
            TransferredTitleOf =
            [
                new HumanMadeObject
                {
                    Id = "https://linked.art/example/object/spring",
                    Label = "Spring",
                },
            ],
            TransferredTitleFrom =
            [
                new Person
                {
                    Id = "https://linked.art/example/person/durand",
                    Label = "Durand-Ruel Gallery",
                },
            ],
            TransferredTitleTo =
            [
                new Person
                {
                    Id = "https://linked.art/example/person/payne",
                    Label = "Oliver Payne",
                },
            ],
        },
    ],
};

Generated from the object the example builds: every property that is set, as object initialisers, with the vocabulary constants where a term is in the registry. The fluent helpers are a convenience, not a requirement; this form and the one as written produce the same JSON.