The ISO speed point is determined based on a set of criteria when the film is exposed and developed under a specific set of conditions. The ISO speed point is for a fixed density of 0.1 above B+F such that the density increases by 0.8 at an exposure 1.3 log H higher than the speed point. This is what is commonly referred to as the "ISO triangle". Therefore development and a gradient are part of the standard. The Zone System is a related but different methodology, not necessarily a "better" one.