The ones I've experienced are best described visually as Braille.
Madness string 793
Fran said she saw something the other day, something dark, still, inexplicable. Something inherently and indescribably horrific. She couldn't describe it.
Any advice that assumes it will fit everybody equally is advice to avoid in most cases. On the other hand, the best advice I have ever been given is to not listen to anybody for advice as it is tarnished by their own experiences.