noun
key block (woodblock printing)
Only when written 墨版
In traditional Japanese woodblock printing, the block that prints the black outlines and serves as the registration guide for color blocks.
浮世絵の制作では、まず墨版を彫る。
In making ukiyo-e, the key block is carved first.
noun
key plate; K plate (CMYK printing)
In modern four-color process printing, the plate that prints black ink; also called the K plate.
CMYK印刷では、スミ版が最後に刷られることが多い。
In CMYK printing, the K plate is often printed last.
Refers to the color blocks or plates, as opposed to the key block/plate.
墨 (sumi, 'black ink') + 版 (han, 'printing plate/block'). The term is used in both traditional woodblock and modern offset printing.