It sure doesn't help when the FAA gets a bit slack (in a few documents, no less) with nomenclature and can't make up their mind as to what's what .. see, for instance,
here or
here, or even,
here or
here.
One expects it between the certification and operations folks but it hurts my head when the certification mob over there has difficulty with consistency ....
For what little it might be worth, the first reference (FTG) does say
"The VMC (commonly referred to as VMCA) requirements... " in the body text .. and then goes on to adopt the Vmca nomenclature as a general usage. At least AC23-8C is consistent with Vmc.
Would never have happened in the days of Air Liquide House ...... as zzuf would well recall ...