Scottish Photographic Federation
Founded in 1903, the Scottish Photographic Federation (SPF) is a non-profit-making body which includes in its objects the discovery, promotion and protection of amateur photography throughout Scotland, and is the only body recognized by international agencies as representing the interests of Scottish Camera Clubs on a national basis. Most Scottish Camera Clubs are affiliated to the SPF and thus participate together, and against each other, in inter-Club, National and International Competitions.
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.