SST Core is optimized in various ways for speed and efficiency.  As a result of the the SST Core is not a general purpose RDF toolkit. This mean, every RDF file generated with SST-Core is valid according to the W3C standards, but not every RDF file can be imported into SST Core. 

In detail the limitation ares.

• every NamedGraph is identified by an URI (URN or URL) without any fragment
• IBNodes are located in exactly one NamedGraph with the same base URI plus a fragment
• NamedGraph IBNode has the same URI as the NamedGraph
• every Datasets is identified by an URI (URN or URL);
• the default graph of a Dataset is also a NamedGraph with the same URI as the Dataset
• blank node can be referenced as object only within the same NamedGraph where they are defined
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