Colour Coding
The Nazis used triangular badges or patches to identify prisoners in the concentration camps. Different coloured patches represented different groups. The colours and their meanings were:
Yellow - Jews
(Star of David) Jewish. This symbol was used prior to the camps in the ghettos and when Jews were in the general population
Pink - Homosexuals
Gay men convicted under Paragraphs 174, 175 and 176 of the Reich Penal Code
Purple - Jehovah's Witnesses
Red - Political Prisoners
Black - Asocial/Roma
Green - Criminals
Colour Coding - In Detail
The "Asocial" category was, perhaps, the most diverse, including prostitutes, vagrants, murderers, thieves, lesbians, and those who violated laws prohibiting sexual intercourse between Aryans and Jews. In addition, while the brown triangle was used for gypsies under certain circumstances, they were more often forced to wear the black triangle categorizing them as "asocials."
Some patches included letters on the triangles to further distinguish among the various groups in the camps. Most commonly, the letter indicated nationality, e.g., "F" for (French), "P" for (Polish), "T" for tschechisch (Czech), etc., but it could also denote special sub-categories of prisoners. For example, the white letter "A" on a black triangle signified a labour disciplinary prisoner, while a black "S" on a green triangle identified a penal prisoner. In addition, the word Blod on a black triangle marked mentally retarded inmates, and a red and white target symbol set apart those who had tried to escape.
For Jewish offenders, triangles of two different colours were combined to create a six-pointed star, one triangle yellow to denote a Jew, the second triangle another colour to denote the added offence. For example, a Jewish criminal would wear a yellow triangle overlayed by a green one; Jewish homosexuals wore pink triangles over yellow.
Outside the camps, the occupying Nazi forces ordered Jews to wear patches or armbands marked with the star of David, though the specific characteristics of the badge (size, shape, colour) varied by region. For example, some yellow stars were marked with a large "J" in the centre; while elsewhere the patches had "Jude" (or "Jood," "Juif," etc.) stitched in the middle. Those who failed to wear the star were subject to arrest and deportation, a fate that frightened most Jews into compliance even though the patch subjected them to restrictions, harassment, and isolation.
Source: Abraham J. Edelheit, and Hershel Edelheit, History of the Holocaust: A Handbook and Dictionary (Boulder, CO: Westview Press, 1994), pp. 218, 239, 266, 448.