Well CJ, in this case it can be understandable unless you 'know'. Pretty much every other driver, patch, and application in the computing world users a version numbering scheme of some sort.
DX9.0c does not (it does but it's not obvious). Why they didn't call it 9.0d, 9.0e, etc or something similar I don't know, but it's pretty confusing. So I can excuse the average person from not understanding this non-versioning system used for DX.