Were talking about tattoos on human skin being used as a barcode mate, there sole purpose was to de-huminise people to the status of a number to make the atrocities less seem less real, After all it's easier to murder a number than a person.
The numbers were for record keeping purposes
One thing that the Germans were brutally efficient with was record keeping
They kept records for absolutely everything and these records helped a lot of people on to the end on Mr Pierrepoint's Noose post war.
For instance every person who was sent to a death camp went by rail
The German Railway "issued" every passenger a third class single (no need for a return)
The cost of the ticket was then reclaimed back from Central Government so that the journey, crew's wages, fuel etc could then be accounted for.
After the bombing of Dresden experts from the local concentration camps came in to manage the clean up.
They logged everything, piled the bodies up in the main square and used flamethrowers to dispose of the bodies en-masse.
De-humanising the killing was never an issue for the Germans.
The amount of people needing killing was the issue and why the camps became industrialised.
The Einsatzgruppen (translated means special action units) never had more than 3000 men serving in them.
They are credited with killing more than a million people.
In two days in Kiev aided by collaborators and local police they shot 33,771 Jews.
You read that correct in two days they shot 33,771 women, children and men.
The wounded were buried alive.
The problems for the Germans was not the killing but the amount of ammo needed to carry it out and the size of the pit needed for all the bodies.
All of which needs to be accounted for.
One unit that was very good at shooting people and committing crimes against humanity was the 14th (Ukrainian) Waffen SS Grenadier Division.
Not so good on the battlefield where they reportedly dropped their weapons and fled but utterly ruthless with Polish and Ukrainian civilians.
They spent most of their war retreating and at wars end were in Austria where they managed to surrender to the British Army.
Stalin wanted them back in the Soviet Union where a single bullet to the back of the head was waiting.
They were taken by ship to Britain and put in a camp near Lockerbie.
The Pope personally appealed to the British Government to save them as they were all good Catholics
They were allowed to remain with most staying in Scotland where they found work as lumberjacks and other jobs and adopted a disguised Polish nationality.