The custom layout folks should have a layer map file. We started with this and hacked the stream map fiile.Originally posted in cdnusers.org by email@example.com
Each layer is associated with layer numbers.
It has the following syntax:
M1 NET,SPNET,VIA,PIN AA BB
M1 FILL AA BB
V1 VIA CC DD
Repeat this for all your metal/via layers. The numbers (AA BB) and (CC DD) can be found in the custom layout stream map file.
If you want text labels add the following as well :
NAME M1/PIN AA BB
This is also documented in