[IamMatt]

Thank you, Alaska Ump, that was my point. I think the strict interpretation of the language of the rule is illustrated in your first example--the rule describes one situation of intentional interference and a second situation of interference without requiring it to be intentional.

I just wanted to know which way the rule was interpreted and enforced, because the rules were not written by grammarians and have some grammatical errors. So my question remains, are umpires taught (and is the rule enforced) that both types of interference MUST be intentional for the runner to be out, or only that interference with a batted or thrown ball must be intentional but that any interference with a play on the runner--intentional or not--results in the runner being called out?

If the former, then they should edit the rule to look like your second example (or just delete the second instance of the word "interferes") so the rule could not be interpreted two ways. If the latter, then the rule is written as it is to be enforced.

Which way is it interpreted and enforced?