I have a hard time distinguishing some of the colours, it would be nice if hashing or other marking was also used.

Yes, colour confused. Why do you ask? (I perceive some pinks and purples as grey and my favourite brown shirt is actually green, according to those who can see all colours properly. I also have a problem with faint red, but bright red isn't a problem: I've never seen Mars as red, but stop signs and stop lights are quite a fine, bright red, thank you.)