In case people are wondering:<p>&quot;SDV&quot; has been in use since at least 2011: <a href="https:&#x2F;&#x2F;scholar.google.com&#x2F;scholar?cluster=10460039591121716316" rel="nofollow">https:&#x2F;&#x2F;scholar.google.com&#x2F;scholar?cluster=10460039591121716...</a><p>The level classifications appear to date from 2013: <a href="http:&#x2F;&#x2F;www.nhtsa.gov&#x2F;About+NHTSA&#x2F;Press+Releases&#x2F;U.S.+Department+of+Transportation+Releases+Policy+on+Automated+Vehicle+Development" rel="nofollow">http:&#x2F;&#x2F;www.nhtsa.gov&#x2F;About+NHTSA&#x2F;Press+Releases&#x2F;U.S.+Departm...</a>