Maybe Strich stands for the Angle Unit.
I have found the followed informations on the german wikipage for Strich (Winkeleinheit).
There's a nautical Strich and a artillery Strich. The last one is also called mil.
I think the document is using the artillery Strich, which means they are using 6400 Strich for 360°.
Or for better conversion 1 Strich is 0,05625°.
I have no idea if this is the right unit, but it could be a first point of reference for your search.