▶ ▼ ▲ ◀ ║ ╒ ╓ ╔ ╕ ╖ ╗ ╘ ╙ ╚ ╛ ╜ ╝ ╞ ╟ ╠ ╡ ╢ ╣ ╤ ╥ ╦ ╧ ╨ ╩ ╪ ╫ ╬
Unicode Math symbols: http://unicode.org/charts/PDF/U2200.pdf
Arrows : https://symbl.cc/en/unicode/blocks/arrows/
& https://symbl.cc/en/unicode/blocks/miscellaneous-symbols-and-arrows/
& https://en.wikipedia.org/wiki/Supplemental_Arrows-C
Line drawing: https://symbl.cc/en/unicode/blocks/box-drawing/
BOX drawing: https://en.wikipedia.org/wiki/Box-drawing_character
includes half-length lines, light & dark, etc.
TRS-80 and other 1970's chars: https://en.wikipedia.org/wiki/Box-drawing_character
← ↑ → ↓ ⇐ ⇑ ⇒ ⇓ ⇦ ⇧ ⇨ ⇩ ⬅ ⬆ ➡ ⬇ ⭪ ⭫ ⭬ ⭭ (dashed) ↰ ↱ ↲ ↳ ⮠ ⮡ ⮢ ⮣ ⮤ ⮥ ⮦ ⮧ ↶ ↷ ↻ ┌ ─ ╌ ┬ ┐ ├ │ ┼ ┤ └ ┴ ┴ ┘
Half-height lines, etc.: https://www.lennyfacecopypaste.com/text-symbols/line.html
Diagonals and various-width horizontals: https://stackoverflow.com/a/75007033/5651151
⟋ ╱ / ‾ _ ‾‾ ⎽ ╱ U+2571 ╲ U+2572