How to understand Pantone U and C?

Pantone color U & C

A new customer offered Pantone color C for graphic overlay with matte surface, it is not correct. He should offer Pantone color U for matte surface and Pantone color C for glossy surface.

Pantone color C is usually for coated paper with glossy surface; while Pantone color U is usually for uncoated paper with matte surface. But in contrast, UV coated PET or PC usually has matte surface, while uncoated PET or PC usually has glossy surface. Therefore, in membrane switch industry, we just use Pantone color C for glossy surface and Pantone color U for matte surface, which is no relation to “coated” or “uncoated”

Please check attached Pantone color card No. 877 U and 877 C, it is clear that 877 U has matt surface and 877 C has glossy surface; at same time, 877 U and 877 C have different color.