Which is a much lighter penalty than offensive pass interference. As you can see from the case play, an ineligible blocking down field is guilty of multiple fouls. Restrictions against blocking down field apply to all A players, not just ineligible players. An eligible receiver blocking down field on a forward pass play is also guilty of OPI.

Then you've been citing the wrong rules section. The blocking per se is covered under 9-3, "illegal blocking", specifically 9-3-1(b).

Actually we haven't but I'm glad you've found more evidence disproving your intereptation on your own. Notice that 9-3-1-b penalty references 7-5-10 and that the case play is numbered 7.5.10.

Consider 9-3-1 as examples of illegal blocks because all of those are defined as particular fouls in other rules (Rule 6, Rule 7 and further in Rule 9).

Opi --
 

It was my understanding that any lineman such as "Lineman A77 is blocking lineman B56 5 yards beyond the neutral zone on a pass that crosses the NZ." Is an illegal receiver down field --- but its NOT OPI unless he actually interferes with .....

And just what would blocking him be:confused:
Remember, all of B is eligible.

I know, I forgot that it's still called "pass interference" even with the reference under "illegal blocking". That's been true for a very long time, but somehow I'd hallucinated that it'd been reclassified a few years ago to cover separately pre-pass and intra-pass interference by A.

But they way they wrote it (and they wrote it a long time ago) is misleading. it would be clearer if they simply said that blocking an opponent downfield was illegal under the circumstances.

The OPI call in the FSU - Notre Dame game last night was the perfect example of blocking down field being illegal.