There are plenty of articles which explain how to create a wordpress plugin. I'm not looking for that, I'm looking for a schema of the core architecture of a wordpress plugin (an UML class diagram and sequence for example).
Has somebody seen anything like that somewhere ?
Update: I know plugin can be as simple as a function. It's not my question. My question is about the architecture of the CALLER that calls the plugin, that is the architecture of the SYSTEM pertaining to the call of the plugin.
At least in which PHP module(s) is it implemented by the Wordpress Core System files ?