This is a feature in many engine, for example I have used Ogre3d. So I want to ask If A7 support it. It will be great if many character could share the same skeletal animation, that will make the game smaller, also make update easier

No, sharing bones won't make the game smaller. Bones do not occupy any noticeable memory. Its advantage is easier editing: sharing bones allows you to assign standard bones sets and animations to models in the editor.

MED does not support this, but many editors do, and if you create a model with such editors it is of course also supported by the engine.

so It mean A7 doesnot have bone sharing, right? So I can not use the same animation assets for many models,but must export per models.?

Yes, you must export a model to the MDL format before you can use it in the engine.

okie, maybe I will make more clear
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I have many character share the same animation. The share the same skeleton in 3D apps

I export 1 models with skeletal animation as mdl.

Now I want to reuse the skeletal animation in the exported mdl for other model, that will be export as static mesh with bone, no animation. So in this case, A7 will support sharing skeletal animation, is it true.? I find in manual but nothing about skeletal animation calling from other entity, only the ent_animate

could you get more specific?

just kidding - jcl made himself perfectly clear, didn't he? it's not supported by the engine itself, but if you use an editor which supports shared skeletal animations you can export your model for a7.
this feature is not a engine feature but an editor feature.

joey.