Square alphabet created by Lewis Carroll ~1891: left top corner is always
marked, other corners are either connected, dotted, or skipped; encoded
numerically and drawn as svg path.
Allows for 34 possibilities with top left anchor:
2^³ (3 dots, only used for A,U,V)
+ 2^²⋅4 − 2² (2 dots with 1 line, 3 unused)
+ 2^¹⋅4 − 2⁰ (1 dot with 2 lines)
+ 2^⁰⋅4 (3 lines)
+ 2⁻¹⋅4 (2 parallel lines)
+ 2⁻²⋅4 (square)
Reference: <http://www.lewiscarroll.org/tag/nyctograph/>