Receivers blocking on a pass behind the line of scrimmage

[riffraft]

I was under the impression that a receiver can block downfield in the NFL as long as the pass was completed behind the line of scrimmage. However someone pointed out to me a rule that says a receiver cannot block more than one yard downfield on a pass play.

Any NFL rule people know the answer?

[goodgrr]

"If an offensive player blocks a defensive player more than one yard beyond the line of scrimmage before a pass has been touched, it is a foul for offensive interference"