Thanks for your interest in ORM and how it relates to SBVR. I'm not sure I understand your question, but reference (identification) in ORM is handled basically as follows.
Values (lexical objects) are constants that identify themselves, e.g. the country code 'AU'.
Entities (nonlexical objects) are identified by definite descriptions (e.g. the Country that has CountryCode 'AU') expressible via a reference scheme that maps each instance of the entity type (e.g. Country) onto one value (or multiple values if the reference scheme is compound) via the reference relationship(s) involved.
For example, using the reference scheme Australia(.code), the entity Australia maps to the country code 'AU' as an instance of the reference type that is the binary relationship Country has CountryCode.
Hope this helps