what is the red 'x' in the schematic?

[J.Kwon]

I don't think it means cut..

[bjorn-spockeli]

If you're referring to the red x markings in our Reference Circuitry Schematics, see below, then as @RK correctly points out they mean N.C , i.e. No Connection.

[J.Kwon]

Sorry, my question was very abstractive. I add some pictures with green arrow. What does it mean? Unlike 'x' in the picture you add, the lines in the picture I add are linked.