There's a Lua 5.03? I know there's a Lua 5.02 release 2 version and 5.1 beta. The only bytecodes I've looked at are those of 4.01, 5.02r2, and 5.1b1, and it definitely looks like it's a variant of 5.02r2. Also, I should mention that I don't know how to program in Lua - I can understand Lua code but have never made a Lua program. I just examined the Lua source (which is in C) and the format of compiled Lua scripts.