The name of the application entity associated with this Field, or to be more specific, the name of the application Entity containing an attribute corresponding to this Field which will be used to populate the Index based on the parent Search Service definition. This information is needed for synchronization of application data with the Generic Search Server - all entities that are listed as being related to Search Service Fields will be registered with the SearchController (see Search Controller) and monitored for inserts, updates, and deletions. It is vitally important that the entityName attribute be populated with the appropriate values; omitted or invalid entityName attributes may result in invalid Index updates over time.