Coefficient of Friction, commonly called C.O.F., is used to evaluate the relative slip resistance of floor surfaces.
Avoid slip and fall situations by always properly specifying floor not wall tile for flooring surfaces, no matter the texture. Whoops!
While a typical standard is .6 static COF, the new ANSI standard sets a minimum dynamic coefficient of friction (DCOF) rating of 0.42. Read this article for a more thorough explanation. You may have codes or brand standards to follow that will determine the minimum COF for you.