Now that you have seen some of the development tools in AX, let's have a look at how AX is built from a technical perspective.
We will look at the following concepts:
Dynamics AX 2012 consists of 16 application object layers that contain all the elements you see in the AOT. These 16 layers are basically formed out of eight core application layers and a patch layer for each core layer.
These layers can be looked at as an onion with multiple layers; the lowest layer or core application layer being the SYS layer and the outermost layer being the user layer USR.
So when any application element is being executed, the system will look at the outermost code layer ...