The alignment is a LineString geometry (i.e., Geo-Polyline) that must be contained within the domain and usually represents the path of a river. It can be seen as drawing the river on the map as a LineString. Similar to the refine-ment, it might be necessary to define several alignments for a context if tributaries and other river features exist. A context can have several alignments as long as they do not in-tersect each other. Unlike refinements, which require at least one to be defined, alignments are optional if the refinements provide enough detail to create the mesh grid. The user can assign a single property to alignments, called CL.