Core 3.0 Literal Value Types are closed

Core 3.0 specifies a closed set of data types for literals [1].

Is there any advice/suggestion on how an implementation should deal with resources and their shapes when other data types are involved?

For example, I work on an application that uses xsd:duration internally, and currently the OSLC representations of that type is identical and hence non-compliant. We could live with this non-compliance, (ii) refrain from exposing resources of such types on the OSLC API, or (iii) pick some other data type that is supported and map values into that supported type. For (iii) xsd:string comes to mind.

What is the preferred approach?

[1] http://docs.oasis-open.org/oslc-core/oslc-core/v3.0/cs01/part6-resource-shape/oslc-core-v3.0-cs01-part6-resource-shape.html#property-shape, "Literal Value Types"

Suggestion: Core 3.0 data types should be open, or at least more generous that the current small set.

Core 2.0 suffers the same issue; guidance on how a core 2.0 implementation should deal with unsupported types would be useful.