Hierarchical structures in RDF schemas

Dear All,

I'm currently trying to define an RDF schema for a representing hierarchical 
video metadata.

I have a top level class called "VideoDoc" and then subclasses of VideoDoc 
called "Sequence", "Scene", "Frame", "Object".

I have created a property "contains". I would like to specify that VideoDocs 
can only contain Sequences, Sequences only contain Scenes, Scenes only contain 
Frames and Frames only contain Objects. Although a property can have multiple 
domains, it can have only one range e.g.

<rdf:PropertyType ID="contains"
   <rdfs:domain rdf:resource="#VideoDoc">
   <rdfs:range rdf:resource="#Sequence">
</rdfs:PropertyType>

Is there any way of defining this multilayered structure without using multiple 
contains properties i.e. contains_sequences, contains_scenes, contains_frames 
etc. which is tedious and repetitive?

I would appreciate your views on how best to do this.

Regards,
Jane Hunter
+----------------------------------+---------------------------------------+
| Dr Jane Hunter                   | Senior Research Scientist             |
| DSTC Pty Ltd                     | Distributed Systems Technology CRC    |
| Level 7, General Purpose South   | Tel   : +61 7 3365 4310               |
| The University of Queensland     | Fax   : +61 7 3365 4311               |
| Queensland 4072, Australia       | Email : jane@dstc.edu.au              |
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| http://www.dstc.edu.au/RDU/staff/jane-hunter.html                        |
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