Are you sure its not CVVT? Continuously Variable Valve Timing Control System.

I'm sure. The first C is outlined and then follows is the vct.

2005, Nissan Altima 4 Door Sport Sedan, 2.5 Liter 16 Valve CVCT 4 Cyl. EFI/Gas

CVCT = cute, very cute transportation (an English translation)......

The link below discusses VCT and has detailed engine photos. See if this helps. I don't know what the first C would mean, but VCT does seem to fit.

GG

Here is a link that might be useful: Nissan link

Continously Variable Camshaft Timing.