From publisher blurb:
Labyrinth Lord Non-Human PCs Across the Ages
This book celebrates one of the great and unique joys of playing Labyrinth Lord: adventuring with non-human player character types from all three early eras of the Original Game in the same party.
Labyrinth Lord allows you to play all of the earliest versions of Dwarves, Elves, and Halflings, whether they're from the 1974 Original Edition Game, the 1981 B/X Game, or the 1977-1989 Advanced First Edition Game. The rules for these characters are in Original Edition Characters (OEC), core Labyrinth Lord (LL), and the Advanced Edition Companion (AEC), which also adds the Gnome, Half-Elf, and Half-Orc from the Advanced era. All such characters are fully compatible and can even be in the same party, thus allowing for thrilling situations where players can potentially experience up to three different early game eras simultaneously.
This Codex is designed to help players fully appreciate this amazing game feature and make informed choices when selecting character types for them. It has three purposes:
Provide handy reference summaries of the OEC, LL, and AEC versions of the three core races side-by-side, as well as the three AEC-only races, allowing for gamers to compare, contrast, and select
Present optional non-human trait tables for customizing non-human PCs for OEC, LL, AEC, the Original Game, and other retro-clones - over 60 new traits!
List other sources of Labyrinth Lord non-human PC rules and new non-human types