The original Schengen agreement mentions
a transit visa authorising its holder to pass through the territories of the Contracting Parties once, twice or exceptionally several times en route to the territory of a third State, provided that no transit shall exceed five days.
It would seem this no longer exist (see for example https://ec.europa.eu/home-affairs/what-we-do/policies/borders-and-visas/visa-policy/apply_for_a_visa_en). When was it abolished?
This page seems to indicate it was abolished on 5/4/2010 with the entry into force of EC810/2009:
Pursuant to the Visa Code (EC Regulation no. 810/2009, which entered into effect on 5 April 2010)
[...]
Transit (type B), type of visa abolished by the above Visa Code. As of 5 April 2010 Transit visas are all type C
Note that the text of the regulation makes no reference I could find to that type of visa, so I can't say for sure whether they were abolished at this time or previously.
It seems type B visas were still issued at the border (but with great difficulty) around 2006 (see https://journals.openedition.org/conflits/15743, point 31), though.
