As originally published, WFRP did not include the concept of critical success or failure on die rolls. Since it is a popular and useful thing to have, however, many people came up with ways of handling it. Unfortunately, they did not all come up with the same way.
Today, there are two commonly-seen definitions of a critical success/failure in WFRP: A die roll of doubles (11, 22, etc.) and a roll which is 30 or more above/below the number required for success. I find both of these to be useful in different situations, so, for clarity, I refer to a roll of doubles as "critical success/failure" and a roll 30 or more above/below the target value as an "extreme success/failure". These can, of course, combine, such as when you have a 50% chance of success and roll an 11; since it satisfies both criteria it is both an extreme success and a critical success (or an "extreme critical" for short).
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