From what I can tell the model role token is not listed under the field content in the main bom editor.
In in draŵing prototype page header this can be added an used.
Model is is important in the aspect of numbering, draŵing production, draŵing style content. Seems strange it is not something in the bom that can be used to help identifie parts and assemblies.
can model role be added to bom system.