In addition to the 10 application object layers in Microsoft Dynamics AX, there are also patch layers. The patch layers are called SYP, GLP, BUP, VAP, CUP, and USP. This topic describes the patch layers and why you should use them.
The patch layers are designed to make it easy to incorporate updates in your application. The basic idea is that when a minor update or correction is made, it is distributed in a patch file, for example, Axsyp.aod. When a patch file is present, the modified objects in the patch file take precedence over the regular application objects and are automatically used. The following illustration shows the application object layers and the patch layers.
The patch files use the same application object number series that the regular files use.
Using patch layers allows you to easily create and distribute an update, for example, by using the Internet, without interfering with the existing application. When you subsequently incorporate the update in the regular layer file, you can delete the patch file that is named Ax??p.aod and the index file Axapd.aoi.