From Valve Developer Community
This article contains speculation that needs to be confirmed.
There are several representations of a model in Source:
- Model index
- An integer unique to each model. Same on all clients as the server. Acquired from the return value of
PrecacheModel()on the server and after that
CBaseEntity::GetModelIndex()on both client and server.
- A handle to an internal engine representation of a model. Can be passed to engine functions, but does nothing on its own. Shared between all instances of a model.
- A MDL file mapped to memory...but each entity has a different one? Can be queried for all sorts of data, but not modified. Despite being an engine class all source code is in the mod SDK.
- Client-side handle to a model instance. Used by the model rendering system.