Moving Screen Violation

[Ralph Stubenthal]

I do not understand what a moving screen violation is or even if there is such a thing. I know that there used to be one mentioned from time to time. I understand the block/charge rule, but, in the screen, the roles are reversed. My question is: is the same rule in effect as in the block/charge rule as pertains to contact? Also, is there ever a violation when there is no contact(hence, the moving screen violation?) In summation, would someone please explain the rule on screening.