Character Usage Guide

Quick reference for ASCII vs. Unicode character usage in CRUMBS codebase.

Rule of Thumb

Code = ASCII only. Docs = Professional typography allowed.

Code Files (.c, .cpp, .h, .hpp, .ino, .py)

❌ Never Use

Don’t	Do	Context
I²C	I2C	Comments, strings
90°	90deg or 90	String literals
— (em-dash)	-	Comments
– (en-dash)	-	Comments, ranges
' ' (curly quotes)	'	String literals
" " (curly quotes)	"	String literals

Why: Compiler compatibility, text editor safety, terminal display issues

Examples

// ❌ BAD
/* Initialize I²C bus at address 0x08 — default config */
printf("Set servo to 90°\n");
float range = 0.0–1.0;

// ✅ GOOD
/* Initialize I2C bus at address 0x08 - default config */
printf("Set servo to 90deg\n");
float range = 0.0 to 1.0;  // or: 0.0-1.0

Configuration Files (.json, .ini, .properties, CMakeLists.txt)

Rule: ASCII only - maximum tool compatibility

Documentation Files (.md)

✅ Allowed (Enhances Readability)

Character	Usage	Example
– (en-dash)	Ranges, connections	4–31 bytes, Arduino–Linux
— (em-dash)	Punctuation, breaks	CRUMBS — a protocol library
Box-drawing	Protocol diagrams	┌──┬──┐
Curly quotes	Narrative text	“Controller sends…”

❌ Not Allowed

• Emojis (except badges/shields in README)
• Decorative Unicode symbols
• Non-standard punctuation

Examples (Documentation)

<!-- ✅ GOOD -->

- Message format: 4–31 bytes
- CRUMBS is lightweight — designed for embedded systems

<!-- ❌ BAD -->

- Message format: 4-31 bytes (use en-dash in docs)
- CRUMBS is lightweight - designed for... (use em-dash in docs)

README Badges

Emoji/shields from badge services (shields.io, img.shields.io) are fine in README files only.

Summary

File Type	Rule
.c .cpp .h .hpp .ino .py	ASCII only
.json .ini .properties .cmake	ASCII only
.md (docs/)	Professional typography OK
README.md	Typography OK + badges OK

When in doubt: Use ASCII. It always works everywhere.