Here's where I'm at:
Whatever HDSM is or was, AV has invested significant r&d$ into it.
AV considers HDSM a trade secret and would move to protect it.
With the resources AV has they would be able to acquire some patents revolving around 'HDSM' even if not exactly the ones they want.
AV, even if holding multiple valid applicable patents, may still wish to bury the patent docs themselves, as much as possible from prying eyes like a competitors or John's.
Therefore, I think there are some patents issued, or at the very least pending, for that secret and in-homogenous sauce known as HDSM.
My guess is that they are "hidden", either by a founder or better yet, held by an IP holding company which grants a perpetual license to AV, thereby increasing their "security thru obscurity". The patent most likely doesn't even contain the acronym HDSM to avoid simple discovery.
Now that they are publicly traded one would think this in some way would be disclosed and there would be a trail to follow in their annual report.
As for undisclosed A's assertation:
It's really insignificant if a patent exists, but HDSM is a trademark at this time that applies to anything they do with technology. Protected by Patent or not.
This is true if there is no 'secret sauce', i.e. no applicable/substantial/enforceable/patentable technology. Then as A implies the actual letters H D S M are more valuable than any actual underlying technology and the trademark is needed to protect the real asset.
That would make it on a par with the "Retsyn" in Certs. No offense.