Status: core attribute
Description: Specifies the person's relationship(s) to the institution in broad categories.
Format: Only these values are allowed:
Number of values: multiple
Notes on usage: This attribute, like eduPersonScopedAffiliation, enables an organisation to assert its relationship with the user. This addresses the common case where a resource is provided on a site licence basis, and the only access requirement is that the user is a bona fide member of the organisation, or a specific school or faculty within it. If there is a value in eduPersonPrimaryAffiliation, that value should be stored here as well. This attribute may appear suitable for controlling access to, for example, an academic licensed commercial software package. However, this is usually not the case; such licenses have greater constraints than just eduPersonAffiliation=faculty. In most cases an academic user must also agree to use the application for only academic purposes and perhaps accept obligations such as acknowledging the owners or reporting results in a particular way.
There is a knowledge base article available that explains how to write a Shibboleth IdP script to present attribute:
Notes on privacy: eduPersonAffiliation should be used when the service provider does not need confirmation of the security domain of the user. Service providers who do need the security domain information should ask for eduPersonScopedAffiliation instead.
Several values of eduPersonAffiliation are regarded as being "contained" within other values: for example, the student value is contained within member. It is recommended that identity providers have the ability either to maintain these multiple values for a given individual, or otherwise provide the ability to release either value as appropriate for a particular relying party. For example, although some relying parties might require the release of the more specific student value, a different relying party that only requires the less specific member value should only be sent the less specific value. Releasing student in this case gives the relying party more information about the user than is required, raising privacy and data protection concerns.
Despite the recommendation above that identity providers should be conservative in what they send, relying parties are recommended to be liberal in what they accept. For example, a relying party requiring member affiliation should also accept student, staff, etc. as alternatives.