Classes or enumerations can be identified by their name and the name of the schema (class or feature identification system) of which they are a part. If the type name has the value String, then optionally, a string length may be specified. For example, an attribute may be identified as being of type String (30). In this case the values for typeName and optionalStringLength are String and 30, respectively. With other types, optionalStringLength should not be specified.
The default schemaName is SAIF (referring to the set of classes which are part of the SAIF specification:
Integer, Time, Point, etc.). If it is assumed that an object must be an instance of the class identified, and not one of its subclasses, direct is true. If the object may be an instance of a subclass of the class identified, then direct is false.