The age limit for Oberstleutnant-rank officers is 61. The Oberstleutnant's shoulder straps in Army and Air Force are marked by two vertically aligned starts above oak leaves. The Bundesgrenzschutz police force used the rank Oberstleutnant until 1976, and was subsequently replaced by the terms "Polizeioberrat" and "Polizeidirektor" during the government's effort to differentiate between West Germany's police and armed forces. The Wehrmacht (1935-1945) of Nazi Germany used the rank of Oberstleutnant for Army and Air Force, much in the same style the Bundeswehr does. The Waffen-SS (1933-1945) used the rank "Obersturmbannführer" as an equivalent. The National People's Army (1956-1990) of East Germany used the rank Oberstleutnant (abbr. OSL) for its army and air force, whereas the Volksmarine used the term "Fregattenkapitän". Austria's armed forces, the "Bundesheer", uses the rank Oberstleutnant as its sixth-highest officer rank. Like in Germany and Switzerland, Oberstleutnants are above Majors and below Obersts. The term also finds usage with the Austrian Bundespolizei (federal police force) and Justizwache (prison guards corps). These two organizations are civilian in nature, but their ranks are nonetheless structured in a military fashion. In Switzerland, Oberstleutnant is the fifth-highest officer rank and is, like in Germany and Austria, subordinate to the Oberst and superior to the Major. Because of the multilingual nature of Switzerland, Oberstleutnant-rank officers might also be referred to as "lieutenant-colonel" (French), "tenente colonello" (Italian) or "litinent colonel" (Romansh).