Not sure if this was posted or not…but its a nice tip if your want to preserve the group ID of your model when you go between applications. The Zbrush method is fast…but it lacks accurate control.
When an a model is exported as .obj…Zbrush seperates the mesh by group ID ie : polymesh_Group1000 polymesh_Group2000 polymesh_Group3000 (the number defines the color of the group id)
so when you want to edit your mesh in another 3d app…you will notice that each group is a seperate mesh…now as long you preserve the NAME of the mesh in order to define the color of the Group ID…you can define and edit the group as much u want just make sure it is single mesh with the proper name.
So for every mesh(doesnt have to be contigous) that has a proper name…you will get a Group ID in Zbrush…just make sure you weld vertices when you import.