ltag table

Stores IETF language tags referenced by other tables for Apple-platform language identification.

Scope

• Format family: Apple AAT
• Table tag in JSON: ltag

Overview

The ltag table maps numeric language codes to IETF BCP 47 language tags (e.g. "en", "sr", "zh-Hant"). These codes are used by the name table for Unicode-platform strings and by feat/morx tables for language-specific shaping.

Specs

• https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6ltag.html

JSON Skeleton

{
	"tables": {
		"ltag": {
			"version": 1,
			"flags": 0,
			"tags": ["en", "es", "sr"],
			"_checksum": 0
		}
	}
}

Top-level Fields

• version — number (UInt32). Currently 1.
• flags — number (UInt32). Currently unused, should be 0.
• tags — string[]. Array of IETF BCP 47 language tag strings. Index position is the numeric language code.

Notes

• Tag index 0 maps to language code 0, index 1 to code 1, etc.
• Tags are ASCII strings (also valid UTF-8).
• Preserve _checksum for stable round-tripping.
• Validate with .validate() after edits.