const Employer_keys = 'name'; public $name; } abstract class Recorded extends OrmClass { public $created; public $altered; } class Building extends Recorded { public $address; } class Office extends Building { } class Home extends Building { } class LivesIn extends OrmRelationship { public $since; } Orm::setup(<<<EOF Person to Person as Partner Person to Employer as EmployedBy Job to Employer as Employs Job to Person as EmployeeOf Employer to Office as Owns Person to Home as LivesIn EOF );