Okura Yusoki A Series Manual page 198

10. Now, the central product looks laid in the center of the pattern. However, OXPA
still doesn't know where the central product is within the red doublet. In order to
center the product within the pattern and mate with the red doublet, checking
both [Hrz] & [Vrt] ON at [Mate with center line] and [Cross point] ON at [Mate
center product].
Red doublet
The red doublets represent the external or central lines of the pattern you
are working on, with which all the products are to be mated each other in
positioning.
Cross point
The cross point of both vertical and horizontal red doublets is used to mate
the central product with the center of the pattern. If just either red doublet
would be used, mating a product may be failed.
13-8
Mate product with
the cross point of
red doublet