P.S.
I think this has been suggested already but I am not sure - I think that one should
eventually think of allowing parallel classifications schemes at wikidata. So one could
have an ISO classification
AND a user made classification like similar to the one at
megajoule.org. Frankly speaking
I fear that classifications like the one at
megajoule.org
(at least if I look at the 100 sofar inserted items, (see under technology)) may not be so
overly appropriate for industrial applications.
In particular their data model may be a problem.