Recommendation
If the topic of military hieroglyphs interests you, I heartily recommend the work of Leo Niehorster. In the course of documenting the structure of organizations that fought in the Second World War, Dr. Niehorster has developed the most elegant dialect of NATO symbology I have yet to encounter. He also offers, free of charge, handy guides to the several systems of tactical documentation used by German soldiers and downloads of many of the books he has written about the structure of various units and formations.
You can find the aforementioned works at niehorster.org
ICYMi, funny old piece, "Military Graphics: What they SHOULD Mean"
https://angrystaffofficer.com/2016/02/15/military-graphics-what-they-should-mean/