provenance/manet_proust/1 matches the site

public static Activity Spring_Sold_To_Proust()
{
    var activity = new Activity()
        .WithContext()
        .WithId("https://linked.art/example/provenance/manet_proust/1")
        .WithLabel("Purchase of Spring by Proust")
        .WithClassifiedAs(Aat.ProvenanceActivity);

    activity.IdentifiedBy = [new Name("Purchase of Spring by Proust from Manet").AsPrimaryName()];
    activity.TimeSpan = new LinkedArtTimeSpan()
    {
        BeginOfTheBegin = new LinkedArtDate(1881, 1, 1),
        EndOfTheEnd = new LinkedArtDate(1883, 12, 31).LastSecondOfDay()
    };

    var acquisition = new Acquisition()
    {
        Label = "Ownership of Spring to Proust",
        TransferredTitleOf = [
            new HumanMadeObject()
                .WithId("https://linked.art/example/object/spring")
                .WithLabel("Spring")
        ],
        TransferredTitleFrom = [
            new Person()
                .WithId("https://linked.art/example/person/manet")
                .WithLabel("Manet")
        ],
        TransferredTitleTo = [
            new Person()
                .WithId("https://linked.art/example/person/proust")
                .WithLabel("Proust")
        ]
    };

    var payment = new Payment()
    {
        Label = "3000 Francs to Manet",
        PaidAmount = new MonetaryAmount
        {
            Value = 3000,
            Currency = Aat.Currency("300412016", "French Francs")
        },
        PaidFrom = [
            new Person()
                .WithId("https://linked.art/example/person/proust")
                .WithLabel("Proust")
        ],
        PaidTo = [
            new Person()
                .WithId("https://linked.art/example/person/manet")
                .WithLabel("Manet")
        ]
    };

    activity.Part = [
        acquisition,
        payment
    ];

    return activity;
}

• Role shortcuts AsPrimaryName, AsAccessionNumber and AsSystemAssignedNumber each add a single classification, with the AAT terms Primary Name, Accession Number and System Number.
• Terms outside the registry The vocabulary registry holds only the terms linked.art itself publishes, so a dataset's own concepts, places and people are written with Aat.Term, Tgn.Place and Ulan.Person, giving the id and the label.

var activity = new Activity
{
    Context = ["https://linked.art/ns/v1/linked-art.json"],
    Id = "https://linked.art/example/provenance/manet_proust/1",
    Label = "Purchase of Spring by Proust",
    ClassifiedAs = [Aat.ProvenanceActivity],
    IdentifiedBy =
    [
        new Name("Purchase of Spring by Proust from Manet")
        {
            ClassifiedAs = [Aat.PrimaryName],
        },
    ],
    TimeSpan = new LinkedArtTimeSpan
    {
        BeginOfTheBegin = new LinkedArtDate(1881, 1, 1),
        EndOfTheEnd = new LinkedArtDate(1883, 12, 31, 23, 59, 59),
    },
    Part =
    [
        new Acquisition
        {
            Label = "Ownership of Spring to Proust",
            TransferredTitleOf =
            [
                new HumanMadeObject
                {
                    Id = "https://linked.art/example/object/spring",
                    Label = "Spring",
                },
            ],
            TransferredTitleFrom =
            [
                new Person
                {
                    Id = "https://linked.art/example/person/manet",
                    Label = "Manet",
                },
            ],
            TransferredTitleTo =
            [
                new Person
                {
                    Id = "https://linked.art/example/person/proust",
                    Label = "Proust",
                },
            ],
        },
        new Payment
        {
            Label = "3000 Francs to Manet",
            PaidAmount = new MonetaryAmount
            {
                Value = 3000,
                Currency = Aat.Currency("300412016", "French Francs"),
            },
            PaidFrom =
            [
                new Person
                {
                    Id = "https://linked.art/example/person/proust",
                    Label = "Proust",
                },
            ],
            PaidTo =
            [
                new Person
                {
                    Id = "https://linked.art/example/person/manet",
                    Label = "Manet",
                },
            ],
        },
    ],
};

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.