Identifying a Generator at a Facility

I am looking to adopt a standard for identifying the presence of a generator at a facility or residence at or near the main power disconnect. I have spoken with CEI and they currently have no requirement for labeling. I am proposing a label that would be used to inform responders that an onsite power generator is present and additional measures may be needed to ensure complete power shut down. I would like to suggest a sticker that incorporates the same symbol for a generator that is used on electrical drawings – a circle with a “G” in the center.

Has anyone found or is using a standard for labeling generators, either at the meter base or the main disconnect? Please email Rob Crowe at: fpo@rrcity.com