The markup to define object properties goes as follows:
%%ObjectProperty...
To define a ObjectProperty representing a Person on writes:
%%ObjectProperty livesIn
The object property markup also allows for the definition of domain and range restrictions using annotations:
%%ObjectProperty livesIn @domain: Person @range: City %
In that example for the object property livesIn also a domain (rdfs:domain) as Person and a range (rdfs:range) as City is defined.