It is very useful for specific explanations of things such as the "situations listed below" from 3-F. Most importantly: 6. DECORATION, Formatting, Invisible Objects: If a NON-TEXT OBJECT is pure DECORATION, or used only for visual formatting, or if it is not presented to users, then it must be implemented such that it can be ignored by ASSISTIVE TECHNOLOGY.
Of course, I'm still concerned by how vague 3-A is: "Color must not be used as the only visual means of conveying [something]". So does bold count?
Also, calculating the Contrast Ratios using the Relative Luminance of the text and the background over which it lays using the conditional parts calculations which are piecewise combined to form a normalized value for colors which are not black or white is ... interesting. Anyone know of a tool that will take RGB 0-255 and map it to the Relative Luminance? Bonus points for taking two RGBs in hex and providing a Relative Luminance for both and the associated Contrast Ratio.
5:1 Contrast Ratios that you probably want to avoid:
#009100 : #000000 and #FFFFFF : #AD00FF