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Event layers are based on tabular data. Events are plotted on a map using either x/y or route location field values stored in the event table. Route events can be either point events or line events. The process of displaying route events on a map is known as 'dynamic segmentation'.
Both x/y and route event layers can be served using ArcMap Server. In some cases, however, selections are not rendered properly when using an HTML client.
If the table that the event layer is based upon contains no ObjectID (OID) field, selections on event layers are not rendered using an HTML client.
Tables from the following data sources do not contain an ObjectID field:
� Tables accessed via an OLE DB connection. There are exceptions - see the article in Related Information below titled "Enable support for selections..."
� Delimited text files
� Tables from an SDE 3 database. Feature classes from SDE 3 do have an ObjectID field
� Tables in an ArcSDE 8 database that have not yet been registered with a geodatabase. Unregistered feature classes have an OID field
� Tables in an Access database that have not yet been registered with a geodatabase
To quickly find out whether an event table has an ObjectID field, open the table's Properties dialog in ArcCatalog, click the Fields tab and examine the field list to see if one is of type ObjectID.
This is a known limitation for HTML clients. In order for a selection on an event layer to render properly in HTML client, the event table needs to have an ObjectID field.
If a table is connected to via OLE DB, a unique, not null index for a long integer field can be created. See the article in Related Information below "Enable support for selections...". If there is a non-registered table in a geodatabase, the table can be registered with the geodatabase in order to add an ObjectID field. The table can be exported to a format that automatically contains an ObjectID, such as a geodatabase, dBASE or INFO.