When you open data in Lucy, a layer is created for that data, and added to the view at a specific position in the layer tree. Typically, you want background raster data at the bottom, and your important business data at the top. Otherwise, your business data would not be visible to the user.

To influence the original position of a layer, Lucy introduces the ILcyModelContentTypeProvider. This interface allows you to indicate for each model what kind of data the model represents. A sorting algorithm determines the best initial position for that model and corresponding layer in the view.

On Lightspeed maps, you can also customize the algorithm directly. This is explained in the Initial layer ordering guide.

GXY maps also offer an ILcyGXYLayerTypeProvider. Similar to the model content type provider, it allows you to associate a certain type to a layer. The initial index calculation algorithm for GXY maps uses both the model content type and the layer type to calculate the initial index for a layer. For more information about GXY layer types and the GXY layer ordering algorithm, see the Initial layer ordering reference guide.

More info about the concept of layer type and model content type providers can be found in the Layer type providers and model type providers reference guide.