Jacobus Publicius Alphabets and Flow Direction Symbols
These by Jacobus Publicius (1492) are useful, unless your first impression is that you already know the alphabet. It's about what the symbols mean for flow direction and other attributes in the torus framework.
Letter I has: single column, upward fish and tower. These are upward flow symbols. (A center column is probably bi-directional).
Letter G, used by masonry, is about that expanding outflow vortex spiral shape. ( And you can keep going from that concept to all of creation if you wish).
Letter L, ( or perhaps you see a mason's square symbol sometimes), confirms with a scythe and axe, that the flow direction is upward.
Letter P, with a crozier and a flag on a pole, are downward flow.
Letter A, alpha shape, has lower side flow portals and a top-center portal, the flows on each side have different attributes.
Letter D has nose ring ( horizontal outflow portal).
I could keep going but I'm less certain about the rest. But I've learned from this. Letter F, downward sword and a crutch, the crutch is apparently a downward flow symbol. Letter B seems to be a P and an upside-down P, making it bidirectional flow. Vertical strings in the midline of a lute would also be bidirectional. Letter M has portal rings, which I hadn't considered before, so I'll probably have to revise my understanding of M. I've posted to save these for future study.