Section 1. Adding New Entities

This section covers allowable scenarios for adding entities to the Ed-Fi data model.

1.1. Add New Domain Entity

A domain entity usually represents a real-world noun or concept. Examples in the core Ed-Fi data model include the Student entity, the Student Assessment entity, the Education Organization entity, and so forth. New entities may be added to the Ed-Fi data model.

• MUST contain at least one identity property.
• MUST NOT allow identity property updates for new domain entities that are not in the core Ed-Fi data model.
• MAY contain multiple identity properties.
• MAY include any properties as required/optional/single/collection. 

Please note that if a new domain entity in an extension re-uses a name from the core model (say, myextention.Student) and the same common type is applied to each (edfi.Address), this has caused collisions in some implementations, For this reason, reuse of a core entity IS NOT RECOMMENDED in the case where the same common type appears on both.

1.2. Add New Association Entity

Association entities usually make a logical connection between domain entities (e.g., between a staff member and an education organization to which they are assigned). In the Ed-Fi data model, Association entities almost always carry additional information about the association itself, such as begin and end dates. Associations often carry information specific to the association such as a staff member's specific role at a particular school.

• MUST have a unique name - consider using a semantic differentiator in the name if an Association joining the same two entities already exists.
• SHOULD have a name that concatenates the entities being joined ending with "Association".
• MAY contain additional attributes beyond the reference to the associated entities.
• MAY include any properties as required/optional/single/collection. 

1.3. Add New Descriptor

Descriptors are a customizable list of values mapped for each implementation. 

• MUST NOT include a map type.
• MUST NOT contain "Descriptor" in the name, as this creates redundancy in the name and causes downstream problems.
• MUST NOT contain any additional properties.

1.4. Add New Shared Simple Type

Shared simple types are elements that can be reused throughout an extension.

• MUST have a unique name.
• MUST contain the minimum appropriate details to define a decimal, string, or integer.
• MUST be a shared decimal, shared string, or shared integer.
• MUST NOT include any properties other than the simple type definition.

1.5. Add New Common Type

Common types are reusable types that can be referenced by inclusion in an Extension.

• MUST contain an identity property if used as a collection. MAY otherwise contain an identity property.
• MUST include at least one property from the list below.
• MAY include any properties as required/optional/single/collection.