By default, COmanage Registry accepts identifiers of any format, as long as they are unique for a given type within a CO. That is, two CO People within the same CO may not have the same identifier of the same type.
As of Registry v2.0.0, Identifier Validation Plugins allow for additional validation to take place. Supported use cases include
As of Registry v3.3.0, CO Groups may also have Identifiers, and the same restrictions (two CO Groups within the same CO may not have the same identifier of the same type) applies. Identifier Validation Plugins are called for Identifiers attached to CO Groups.
Plugins must be instantiated (CO >> Configuration >> Identifier Validators) by attaching them to the type of identifier to be validated. Validators can be attached to multiple types (including both Email Address and Identifier types), and a given type can have multiple Validators attached.
To skip availability checks, including all Identifier Validation Plugin calls, use
save($data, array('skipAvailability' => true)).