It’s in the Radiant model manual. (2.4 Tags).
Below is a compilation of excerpt(s) from the radiant model manual and the paposo milkshape tutorial.
Tags are connection points for other model parts and represent the limited hierarchical system of the game. The shape of the tag is a right triangle, where one leg is longer than the other one. The longer leg of the triangle corresponds to the +Z direction, the shorter leg of the triangle corresponds to the –X direction and the gray face (the positive vertex face) looks into the +Y direction. A tag is used to attach models together at “run-time” when the game starts. Why not just put the model where you want them in Radiant then? Why use tags? Because once the models are attached you can control only one of the models and the other models move with it. You can also switch the attached models using a script “in-game”. You can also control a separate animation sequence on the various models instead of making a bunch of animation on the main model.
Basicly they cut down on complex model scripting for script_movers. There is an .md3 to .tag file program (although it seems models tag without them). as well as the tag creation program mentioned. As long as it works and it doesn’t compromise the desired integrity/features of the model to make them (ie wipe out animations on ex. -jagpanther/churchill.md3) then I can’t think of a better way to cheat re-exporting a model.
You can also switch the attached models using a script “in-game”- from rtcw tutorial? how? -zenith.