[meteorite-list] Terminological question: SMB vs. IMB

[Martin Altmann]

Hello list,

 On the occasion of an ebay auction,
 namely NWA 2704 "SMB H4",
I was asked by a collector, what the difference could be between an impact
melt breccia IMB and a "shock melt breccia - SMB".
Honestly I don't know the difference, as I never heard this term "SMB"
before and was thinking, that all shock and melting processes in ordinary
chondrites were caused by impacts.
>From the picture of the auction I can't tell much, as the cut surface of the
specimen is small and it's looking to me not diffrent from an IMB.
Is SMB now a term of the official nomenclature and what shall I respond to
the collector?

Many thanks,
Martin