The badge system in Nazi concentration camps defined and differentiated each prisoner racially, politically and/or sexually.
Yellow Star: Jewish
Green Triangle: Criminal
Red Triangle: Political Prisoner (often Communist)
Black Triangle: “Asocials” (vagrants, Roma gypsies)
Pink Triangles: Homosexuals
Purple Triangles: Jehovah’s Witnesses
If the prisoner was non-German, they had the initial of their place of origin on their badge. If a prisoner fell into more than one category they wore a number of badges (e.g. a Jewish, gay communist would wear a yellow star, pink triangle and red triangle).
Jews were required to wear the yellow badges even before they were interned. Non-compliance, as in Hartmann's case, could lead to deportation.
Note: Hartmann also appears in Faulks's The Girl at the Lion d’Or.