Quick question…
If you have a blade that is ground 5° per side (see picture), and you sharpen it at an angle measured 20° from vertical (how it’s measured on the W.E.), do you consider the edge sharpened at 15° or 20° ? (Setting aside the ‘actual angle doesn’t matter’ argument.) I know you’d document it as being sharpened on the 20° setting, but what do you consider it sharpened at?
Grasshopper… Why do you ask such questions? You know more of angles than the master.
The apex will have an included angle of 40 degrees, so I consider it 20 dps. The primary grind (whether 5 or 10 degrees included) is irrelevant when considering the sharpness of the edge. Angles are always relative to the centerline plane of the blade. Nicht wahr?
Jawohl. At least that is what I also believe. 
Thanks. Measuring from the centerline is what I thought… then I was watching a video yesterday where it was being measured from the blade’s grind, and it kinda threw me, since I hadn’t really thought about it before. Never hurts to ask. 