Data models in the form of eERMs, even if they display entity types and relationship types only, mostly have a rather complex structure. If ERM attributes were included in these models, they would no longer be legible.

eERM attribute allocation diagrams enable you to assign ERM attribute allocations to every entity type and relationship type in a separate model. The object type of the eERM (entity type or relationship type) can be included in this model as an occurrence copy, and the relationships to the ERM attributes can be modeled. It is possible to distinguish whether the linked ERM attribute is a key attribute, a foreign key, or a descriptive attribute. The following figure illustrates an example.

This model type not only enables individual ERM attributes to be represented and allocated, but also displays attribute type groups and their allocations.

An attribute type group represents a group of ERM attributes of an entity type that are closely related semantically. For example, ERM attributes of an entity type that, in their entirety, form a secondary key can be combined to form an attribute type group.

Attribute type groups are represented as follows:

A list of relationships that are available in an ERM attribute allocation diagram is provided in the ARIS Method Reference manual on your installation media.