Civil servants grade insignia on the uniform of 1939/40 was in the form of "horseshoes" worn on the left lower sleeve.
Ranggruppe I was the top group. Stars according to pay grade.
4 stars = Reichsminister
3 stars = paygrade B3a
2 stars = paygrade B3b and 4
1 star = paygrade B5 and B6
0 star = paygrade B7a to B9
Civil service grades and pay grade are found here:https://de.wikipedia.org/wiki/Reichsbesoldungsordnung#Fassung_vom_M.C3.A4rz_1937Typical civil service grades
4 stars = Reichsminister, Reichskommissar
3 stars = Staatssekretär
2 stars = -
1 star = Ministerialdirektor
0 star = Ministerialdirigent
Those civil servants having the right to wear a party uniform or the uniform of a party organization were obliged to wear it instead of the civil service uniform. Ordnungspolizei
of course wore their respective uniforms.