Primary/Secondary Bevel Discrepancy
The 'Primary/Secondary' Discrepancy
There is a divide in the accepted nomenclature denoting the order of bevels. The terms 'Primary Bevel' and 'Secondary Bevel' are often used to mean exactly the opposite thing, depending on who you ask.
The order of bevels, as accepted by the woodworking, metalworking, and engineering trades, counts bevels in order of their deviation from the original flat plane that is altered to make a bevel(a bevel being simply any slope added to an item). So the first bevel cut into a knife is the Primary, the subsequent, wider angles, are 'Secondary', 'Tertiary', and so on, and the bevel that makes up the cutting edge can be any of these bevels. The face is not considered a bevel, as it is the plane that is being altered.
For whatever reason, either through historical convention, or logical re-evaluation, the names of bevels in the knife world are often reversed. The Primary Bevel is always the cutting edge, and the subsequent, narrower angled bevels are 'Secondary', 'Tertiary' and so on. This is likely because the cutting edge is of utmost importance in knives, and receives the most attention.
While the first usage is more widely used throughout different trades, the second usage is supported by a large section of the cutlery world, and promoted by some of the most well-known and respected members of the knife sharpening elite. Due to the widespread implementation of the second method in the knife world, neither method is wrong(usage determines meaning, eventually), but due to the fact that there is never a clear cut consensus on which is “correct”, and the first usage being constantly imported from other trades, this is not likely a debate rested any time soon.