16 Shading Models in total allowed?


I’m trying to add my custom shading model to UE4.26.2.

In ShadingCommon.ush, there is a line of code (ln.18):

define SHADINGMODELID_MASK 0xF // 4 bits reserved for ShadingModelID

to my understanding, it seems UE4 will only support 16 Shading Models in total (due to the SHADINGMODELID_MASK value), and there are already 12 offical Shading Models.

I am just wondering what if I want to add more shading models? Does that mean I can only add 4 more models, otherwise I have to replace existing ones?