The International Fine Print Dealers Association
The International Fine Print Dealers Association (IFPDA) is a non-profit organization of leading art dealers, galleries, and publishers with expertise in the field of fine prints. Members are committed to the highest standards of quality, ethics, and connoisseurship, and to promoting a greater appreciation of fine prints among collectors and the general public. Since its formation in 1987, the Association has grown beyond its original five founders into an international organization with over 165 elected members in thirteen countries. Membership requires a high level of expertise, ethics and professional integrity. Election to membership takes into account years in business, the quality of art offered for sale, exhibitions and published catalogues, as well as community service.
I like the White Galaxy Marker very much for writing on dark paper, and I have used it to cover another color when I needed to disguise a mistake or simply change effect.
For example, I bought an ornament with name SCARLETT spelled on it and by covering the last 't', I was able to give this to someone with a cat named SCARLET.
If color to be covered is a paint or other pen color, that can make the other color "stain" the white marker tip. This can be avoided if one is sure first color is dry before trying to cover it with white.