Basic AU SDK question

[Fred e]

I'm currently looking into the AU API, I wish to make a project setup/template
with as few dependencies as possible to Apple-provided AU code.
I had a look at IPlug and "IplugAU" which only includes these AU headers (Correct me if I'm wrong here)

AudioUnit/AUComponent.h
AudioUnit/AudioUnitProperties.h
AudioToolbox/AudioUnitUtilities.h

and implements a set of functions

static ComponentResult IPlugAUEntry
static ComponentResult GetParamProc(...)
static ComponentResult SetParamProc(...)
static ComponentResult RenderProc(...)
etc.

In which audio rendering/parameter handling etc is done.
Is there anyone here who can clarify this approach to me; (I've been studying the WDL Xcode projects but can't get a clear picture of what's going on, newbie on OSX coding) How does the AU host know which function to call in the component on entry/open/close/processing etc. Where and how is this defined to compiler/linker?
(I'm using Xcode 4)