Constraints: Content model - how to?

Hi:

Naive question, but: Is there any means of specifying content model type
constraints in an RDF schema? Eg in the schema below I'd like to
differentiate between the Nest and Item classes - see comments - but I
don't seem to have a means to express that. Oh, and if I'd further like to
constrain the literal properties to be zero or one? Is this straying into
DAML territory or is there some other way to do this?

Thanks,
Tony



@prefix  : <#> .
@prefix s: <http://www.w3.org/2000/01/rdf-schema> .

# Nest class ( :resource & :collection )
:Nest a s:Class .
# Item class ( :resource | :collection )
:Item a s:Class .

# Resource properties
:resource a s:Property ;
    s:domain :Item, :Nest ; s:range s:Resource .
:collection a s:Property ;
    s:domain :Item, :Nest ; s:range s:Container .

# Literal properties
:access a s:Property ;
    s:domain :Item, :Nest ; s:range s:Literal .
:detail a s:Property ;
    s:domain :Item, :Nest ; s:range s:Literal .
:directive a s:Property ;
    s:domain :Item, :Nest ; s:range s:Literal .
:label a s:Property ;
    s:domain :Item, :Nest ; s:range s:Literal .
:role a s:Property ;
    s:domain :Item, :Nest ; s:range s:Literal .
:type a s:Property ;
    s:domain :Item, :Nest ; s:range s:Literal .