layer

A thematic set of spatial data described and stored in an ArcStorm database or a LIBRARIAN map library. Layers organize a database or map library by subject matter (e.g., soils, roads, and wells). Conceptually, layers in a database or map library environment are exactly like coverages. See also ArcStorm database and map library.

A logical set of thematic data described and stored in a map library. Layers organize a map library by subject matter, e.g., soils, roads, wells, and extend over the entire geographic area defined by the spatial index of the map library.

In radio wave propagation, see F region. 2. In telecommunications networks and open systems architecture, a group of related functions that are performed in a given level in a hierarchy of groups of related functions. Note: In specifying the functions for a given layer, the assumption is made that the specified functions for the layers below are performed, except for the lowest layer.