@zwaarcontrast/ol-graticule-heeresgitter
WWII Wehrmacht grids: Deutsches Heeresgitter (6° Gauß-Krüger on the Bessel 1841 ellipsoid, with Kennziffer-prefixed eastings) and the orange Heeresmeldenetz letter-cell overprint (6 km Kleinquadrate → 2 km Meldetrapeze → 1 km Arbeitstrapeze, alphabet without I).
Sources: Planheft Schweiz (OKH g 23/1, 16 March 1944), Capturing the Complex Histories of German WWII Captured Maps (Powell & Mühr, 2020), and Geodetic grids in authoritative maps – new findings about the origin of the UTM Grid (Buchroithner & Pfahlbusch, 2016).