DAML+OIL documentation ambiguous?

from http://www.daml.org/2001/03/daml+oil-walkthru#restrictions

-----snip------

The next few lines describe a class-specific range restriction. In 
particular, the parent of a Person is also a Person.

  <rdfs:subClassOf>
    <daml:Restriction>
      <daml:onProperty rdf:resource="#hasParent"/>
      <daml:toClass rdf:resource="#Person"/>
    </daml:Restriction>
  </rdfs:subClassOf>

What happens here is that the Restriction defines an anonymous class, 
namely the class of all things that satisfy the restriction. In this 
case: the class of all things whose parent is a Person. We then demand 
that the class Person is a subClassOf this (anonymous) class. In other 
words: we demand that every Person must satisfy this Restriction, which 
in this case amounts to demanding that Persons have only Persons as 
their parents.

-----snip------

This could suggest the default cardinality is 1 in DAML+OIL, perhaps it 
could be made clearer by saying that if a person does have this property 
then it demands....

Hmm, perhaps it is a minimum of 1, come to think of it, I can't find 
where such a notion is explicitly stated.