2.1.1 Schema

The Schema element is the top-level conceptual schema definition language (CSDL) construct that allows creation of a namespace.

The contents of a namespace can be defined by one or more Schema instances. The identifiers that are used to name types are unique within a Namespace. For instance, an EntityType cannot have the same name as a ComplexType within the same namespace. The Namespace forms a part of the type's fully qualified name.

The following is an example of the Schema element:

 <Schema Alias="Model" Namespace="Test.Simple.Model"
 xmlns:edm="http://schemas.microsoft.com/ado/2009/11/edm" 
 xmlns="http://schemas.microsoft.com/ado/2009/11/edm">

The following rules apply to the Schema element.

• The CSDL document MUST have the Schema element as its root element.

• The Namespace attribute is defined for each Schema element. Namespace is of type QualifiedName. A namespace is a logical grouping of EntityType elements, ComplexType elements, and Association elements.

• A schema Namespace attribute cannot use the values "System", "Transient", or "Edm".

• A schema definition can span across more than one CSDL document.

• The Alias attribute can be defined on a Schema element. Alias is of the type SimpleIdentifier.

• Schema can contain any number of AnnotationAttribute attributes. The full names of the AnnotationAttribute attributes cannot collide.

• Schema can contain zero or more of the following child elements. The elements can appear in any given order.

  • Using

  • Association

  • ComplexType

  • EntityType

  • EntityContainer

• In CSDL 2.0 and CSDL 3.0, Schema can contain zero or more of the following child elements.

  • Function

• Schema can contain any number of AnnotationElement elements.

• In CSDL 3.0, Schema can contain any number of Annotations elements.

• In CSDL 3.0, Schema can contain any number of ValueTerm elements.

• AnnotationElement elements MUST appear only after all other child elements of Schema.

All child elements are to appear in the order indicated. For all child elements within a given choice, the child elements can be ordered arbitrarily.