A map view definition can have one or more layers that define contents and layout of the map view. Each layer is of a specific layer type that defines what data can be shown in that layer and how that data is shown. Each layer type also comes with its own UConfiguration that allows the user to fine tune what data the layer presents and how that data is presented.

Within a map view definition layers have a sequence, the sequence defines the drawing sequence, and therefore the Z-Order (ordering of overlapping two-dimensional objects) of the drawn items. Each layer has a name that can be defined by the user.

Some layer types can connect features and/or views to a map view. I.e. layers of these types will render spatial data and other data of features or of the features' observations. Features can be connected to a map view directly, or indirectly by connecting container features or by connecting views. How connected views and container features are handled depends on whether the layer is typed i.e. allowing only features of a specific feature type to be connected, or the layer is untyped i.e. allowing features of any type.

Handling of connected views and features with untyped layers

•View: All member features of the view are used as data source

•Container feature: If the layer's 'Expand container features' option is set all contained features of the container are used as data source but not the container itself. If that option is not set the container feature itself is used.

•Non-Container features are of course used as data source directly

Handling of connected views and features with typed layers

•View: All member features of the view that match the layer's feature type are used

•Container feature: If the container feature's type matches the layers feature type the container feature is not expanded. If it does not match all member features that match the type are used as data source

•Non-Container features are used as data source if the type matches the layer's type