Layer System

General
The layer system in Dynamics AX is an important feature for customization. Elements in the AOT exist in different layers. There are 10 layers available in Dynamics AX. Each layer has an additional patch layer. The layers also define a range of IDs for elements created at this layer.

Version 2009

 * SYS - System elements
 * GLS - Global solutions
 * HFX - Future patch layer
 * SL1, SL2, SL3 - Distributor vertical solutions
 * BUS - Business partner generic solutions
 * VAR - Value added reseller industry specific solutions
 * CUS - Supervisor/administrator company modifications
 * USR - End user modifications

Version 4.0

 * SYS (System) 1-8000
 * GLS (Global Solution) 8001-16000
 * DIS (Distribution) 16001 - 18000
 * LOS (Local Solution) 18001 - 20000
 * BUS (Business Solutions) 20001 - 30000
 * VAR (Value Added Reseller) 30001 - 40000
 * CUS (Customer) 40001 - 50000
 * USR (User) 50001 - 60000

You have to buy licence codes to get access to a certain layer. Typical customization layers are BUS and VAR. If you don't have a license code for a higher level, you are working per default on the user layer.

Customization
One of the greatest features in Dynamics AX is that an element can be defined a multiple layers. The system always takes the element from the outermost layer. In contrast to normal development where you modify the original code, your overwrite an element from a deeper level with an element in a higher layer. So it is still exists in the lower layer but is not visible to the user. All your customizations are therefore on one layer, like VAR or BUS. This makes distribution of your solution as easy as possible. You just take the complete VAR layer and plug it into another application. This can be done by copying the corresponding file.