In the sense that this is an interface with the user of pens, I thought this might be an acceptable place to ask this question, but if it's just application interfaces, then please remove or close this question with my apologies.
Are there manufacturers of whiteboard and or permanent markers that produces one type with cylindrical shafts and the other with octagonal / hexagonal cylinders? This would help people identify the type of marker just by touch rather than having to find the print on the side that says dry-wipe or permanent. It could save us a few calls to facilities to clean permanent marker off the white boards.