Good question. I have always assumed, rightly or wrongly, that whatever is suppressed is converted into whatever is fostered. So at the Astrodome, AT&T, Petco and Comerica, for example, HR's are converted into triples, because those parks have big (-) numbers for HR's and big (+) numbers for triples. At Busch I and Olympic, HR's are converted into doubles, and at Dodger Stadium, HR's are converted into singles (if that's possible). At a park like Safeco, which suppresses everything, I assume the HR's become outs. But I'd be interested in hearing other opinions.