The main part of a map is the tile layer which provides raster graphics representing the Earth surface or part of it, and zero or more layers representing spatial data.

The tile layer is specified by the TileSource property. It may be set to a VirtualEarth tile source (road, aerial, or hybrid). The tile source may be set to "none" in which case no tiles will be drawn on the map. This may be useful especially when other layers such as KML provide enough data for the map visualization.

Note that unless the tile source is "none", the tiles are loaded from a network location when the report runs, which may slow things down considerably.

Except for the tile layer, all other layers are contained in the Layers collection. Currently, three layer types are supported:

• Points. A "points" layer allows to show spatial data as points on the map. A marker is drawn for each data row by the "points" layer.
• Lines. A "lines" layer draws a straight line between two points for each data row.
• KML Layer. KML (Keyhole Markup Language) is an XML based language that allows to describe various geographic information. For more info on KML see http://en.wikipedia.org/wiki/Keyhole_Markup_Language. A KML layer allows to load into the map and show a local or Web-based KML file.

Specifying the Layer Data Source

For each layer in the Layers collection, the layer's own RecordSource (a SQL statement) may be specified. If it is omitted, data (except for KML layers) is retrieved directly from the parent report (filtered according to the current grouping scope). If provided, RecordSource is used on the parent report's connection string.