EDM.String maps to the VARCHAR, CHAR, CLOB, Period, and a few Interval types. When the Framework indicates that a parameter is an EDM.String, the Entity Provider does not have to perform any special processing. It will set the TdParameter.TdType to TdType.Varchar, and invoke the Data Provider for Teradata to execute the SQL statement generated from the information passed in by the Entity Framework. The Data Provider will then send the data to the Advaned SQL Engine as a VARCHAR. When Teradata receives the data it will implicitly convert the data into the Period.