Back to Semantic Sensor Network Ontology.
PLEASE NOTE THAT WE HAVE RESOLVED THIS DURING CALL 28-02-16
See related mail thread https://lists.w3.org/Archives/Public/public-sdw-wg/2017Feb/0195.html
Option 1: do not use voaf
Ontology instances are just instances of owl:Ontology.
Option 2: use voaf in SOSA and SSN
Ontology instances are instances of owl:Ontology and voaf:Vocabulary. UPDATE (28-02-17): voted on and accepted.