At the end of World War Two it was widely assumed that the Nazis running the concentration camps had gassed millions of prisoners in them. At the International Military Tribunal in Nuremberg, which ran from late 1945 until early fall 1946, it was stated in the judgment that millions of people had been gassed and cremated at the Auschwitz camp, which actually comprised a base camp of that name, and numerous satellite camps, the largest of which was at Birkenau, about two miles away. The evidence upon which the International Military Tribunal's judges made their judgment about gassings at Auschwitz consisted of some testimony and a special report prepared by the Soviet Union. The integrity of that Soviet Commission has been put seriously in doubt since their involvement in the Katyn collusion.
The decision of the International Military Tribunal to endorse the claim of gassing at Auschwitz had far-reaching repercussions, because it was stipulated at the time that the judgments arrived at by that tribunal would be binding for all subsequent legal proceedings. Hence, all later trials in Germany on the subject of Auschwitz, whether conducted by the occupying powers or by the Germans themselves, have never contested the gassing since their occurrence was not something that could be disputed. This is also the reason for the holocaust denial laws in some European countries.
The two documents consisted of a letter from the Auschwitz Central Construction Office, which uses the word "Vergasungskeller", and another, also from the Construction Office, which used the term "gasdichte Türme." Both terms were translated as "gas chambers" by the American prosecution, but these are incorrect translations.
It was also mentioned in another thread that gas doors are needed to separate morgue three and its ventilation system from the other morgues. Morgue three is the autopsy room.
It is also likely that such morgues can double up as air raid shelters if necessary along with necessary facilities to sustain life for a time. Living people and cadavars do not exist well together so unburned bodies need to be separated, hence L1.
CODOH have their version https://codoh.com/library/document/904/