ListSourceDataAdapter.DefaultMapItemType Property

    mapControl.Layers.Add(CreateVectorLayer(data));
LayerBase CreateVectorLayer(object data) {
    ListSourceDataAdapter adapter = new ListSourceDataAdapter() {
        DataSource = data,
        DefaultMapItemType = MapItemType.Custom
    };
    adapter.Mappings.Latitude = "Latitude";
    adapter.Mappings.Longitude = "Longitude";

    adapter.AttributeMappings.Add(new MapItemAttributeMapping() {Name = "Name", Member = "Name"});
    adapter.AttributeMappings.Add(new MapItemAttributeMapping() {Name = "Year", Member = "Year"});
    adapter.AttributeMappings.Add(new MapItemAttributeMapping() {Name = "Description", Member = "Description"});

    VectorItemsLayer layer = new VectorItemsLayer() {
        Data = adapter,
        ItemImageIndex = 0,
        EnableSelection = false,
        EnableHighlighting = false,
        ToolTipPattern = "<b>{Name} ({Year})</b>\n{Description}" 
    };
    return layer;
}

    mapControl.Layers.Add(CreateVectorLayer(data))
Private Function CreateVectorLayer(ByVal data As Object) As LayerBase
    Dim adapter As New ListSourceDataAdapter() With {.DataSource = data, .DefaultMapItemType = MapItemType.Custom}
    adapter.Mappings.Latitude = "Latitude" 
    adapter.Mappings.Longitude = "Longitude" 

    adapter.AttributeMappings.Add(New MapItemAttributeMapping() With {.Name = "Name", .Member = "Name"})
    adapter.AttributeMappings.Add(New MapItemAttributeMapping() With {.Name = "Year", .Member = "Year"})
    adapter.AttributeMappings.Add(New MapItemAttributeMapping() With {.Name = "Description", .Member = "Description"})

    Dim layer As New VectorItemsLayer() With {.Data = adapter, .ItemImageIndex = 0, .EnableSelection = False, .EnableHighlighting = False, .ToolTipPattern = "<b>{Name} ({Year})</b>" & ControlChars.Lf & "{Description}"}
    Return layer
End Function