The only marking that I place on the plate holders is a number, usually inscribed on a small sticky-backed circular label. The numbers a semi-permanent, used to identify each holder. I annotate details with regard to the specific holder, it's number, film used, exposuse, how I felt, weather, etc in a small notebook. After film development I will transfer this information onto to the protective film sleeve with a fine tip permanent marker, only for those few negatives that are worth maintaining.