In North America, the "V" grades devised by John Sherman at Hueco Tanks are prevalent having largely displaced use of the older "B" grades introduced by John Gill. The "B" grade system has only three catagories, B1, B2 and B3. B3 problems are those that have only been completed once. B2 as problems that are "harder than B1". B1 problems are those relating to "a hard toprope climb". The "V" grading system currently covers a range from V0 to V15. It is difficult to directly compare bouldering technical grading systems to climbing technical grading systems, however, a V0 boulder problem would relate approximately to the crux of a 5.9+ climb using the Yosemite Decimal System that is also common in North America. A B1 problem was defined by John Gill in 1987 as a 5.12, but in 1969 as a 5.10. This highlights the constant evolution of the "B" scale.
See also: Grade (climbing).