There are a number of identifying white markings on a horse's face and they are so common they have their own names.
A Guide To Common Horse Markings
Markings - gallop to discover
Horse Markings: Your Cheat Sheet on What You Need to Know!
Recoloring –
Thoroughbred Colors and Markings
FACE AND LEG MARKINGS GUIDE TO REGISTER YOUR FOAL - Sugar Creek
What's a Whorl? - Teddie Ziegler Horsemanship
White markings, Pinto, Roan, Leopard Complex And White Horses
Intro to Face Markings
The American Paint Horse-A Colourful Character. – Irish Sport
Know Your Horse Markings
Identifying Horse Parts and Markings - dummies
Normal Facial and Leg Markings by happy-horse-for-life on DeviantArt
Close-up photograph of a deaf horse with typical eye and facial