What do the prefix ‘O’ and suffix 'C' mean in the Venus Diamond opaque shade colour names?

Opaque shade prefix

The prefix ‘O’ (e.g. OLC, OMC etc.) stands for ‘Opaque’. These shades are the least translucent of all Venus Diamond shades. The suffix C in the opaque shades means "chromatic" and emphasis the intensive chroma of these shades.