SN 56.11 Dhammacakkappavattana Suttahttp://www.accesstoinsight.org/tipitaka ... .piya.html
"As long as my knowledge of seeing things as they really are, was not quite clear in these three aspects, in these twelve ways, concerning the Four Noble Truths, I did not claim to have realized ...
As the previous paragraphs indicate, there are three aspects of knowledge with regard to each of the Four Noble Truths: 1. The knowledge that it is the Truth (sacca-ñana). 2. The knowledge that a certain function with regard to this Truth should be performed (kicca-ñana). 3. The knowledge that the function with regard to this Truth has been performed (kata-ñana). The twelve ways or modes are obtained by applying these three aspects to each of the Four Noble Truths.
Hence the (usual) 12 spokes in the Dhamma Wheel.