LEUPOLD 3-9 Vari-X IIc

Hi all...could someone please explain to an old bugger just what the ( c) means VX IIc .
I have had a wee play on the net but just cant seem to find anything.

What's the difference between a Leupold Vari-XII and Vari-XIIC? | Hunting Optics | 24hourcampfire

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Finer adjustments, although still friction and inceased available adjustment. There ya go.
Should post this on the yankee forum so they clearly know the answer ha ha

And of course potentially 29 years younger.
This chart gives year of manufacture.
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Thanks guys,all good.