Should the Diamond display have a 75% RGB limit marker?

Should the Diamond display have a 75% RGB limit marker?

No. A 75% limit on RGB is too restrictive since some colors near green and magenta can be over 100% RGB without causing composite NTSC signal values over 100 IRE. Also, some margin over 100 IRE is OK. It may be acceptable to allow composite NTSC signal levels to 110 or even 120 IRE before transmitters or other processing clips the composite signal.