Is there a universal hike difficulty rating system?
I've been searching the web for some hike rating definitions to fit the commonly used easy, moderate, difficult and strenuous descriptors. I've found a few sets of definitions, but they all differ from one another. Most cover distance and altitude gain, but I've found only one that also covers the ground conditions (scree, roots, scrambling and so on). Is there one universally accepted set of definitions or at least one that is most commonly used in the USA?
Thanks in advance for your response.