Sometimes you want to express facts about facts - say "the triple 'trumpet[hasSize -> small]' hasEvidence high.

Similarly to RDF this cannot be done directly, for an OBL molecule has no ID by itself.

The most appropriate modelling pattern for this problem is called reification: We make a fact "Subject [ property -> Object]" being the subject of another fact by itself.

The fact we want to talk about:

erniesFireEngine hasColor red