'Auster' (i) was the German revised codename for the Studie 'Nord' concerned with the inclusion of Denmark and Norway in Germany’s plans for offensive strategic operations (spring 1940).

The first use of the codename occurred in Adolf Hitler’s order of 23 January 1940 that the current Ausarbeitungsstab (planning group) should be disbanded and its work transferred to by the Oberkommando der Wehrmacht.