simple : A simple parameter can be of any type except for a known (mapped) DVC or an entity. A simple parameter only contains the argument number, such as {0}. When a simple parameter is set, the JDBC type used to set the parameter is determined by the datasourcemapping for the entity. An unknown DVC is serialized and then set as a parameter. Note that most databases do not support the use of a BLOB value in a WHERE clause.

DVC : A DVC parameter can be any known (mapped) DVC. A DVC parameter must be dereferenced down to a simple property (one that is not another DVC). For example, if we had a CVS property of type ContactInfo, valid parameter declarations would be {0.email} and {0.cell.areaCode} but not {0.cell}. The JDBC type used to set a parameter is based on the class type of the property and the datasourcemapping of the entity. The JDBC type used to set the parameter is the JDBC type that is declared for that property in the dependent-value-class element.

entity : An entity parameter can be any entity in the application. An entity parameter must be dereferenced down to a simple primary key field or simple property of a DVC primary key field. For example, if we had a parameter of type Gangster, a valid parameter declaration would be {0.gangsterId}. If we had some entity with a primary key field named info of type ContactInfo, a valid parameter declaration would be {0.info.cell.areaCode}. Only fields that are members of the primary key of the entity can be dereferenced (this restriction may be removed in later versions). The JDBC type used to set the parameter is the JDBC type that is declared for that field in the entity declaration.