I was wondering the same thing. I know that Siemens and Murray are exactly the same and should be listed for each others panels since they are made on the same line, just diferent stickers. I know Siemens will fit in a GE, but a GE doesn't quite fit right in a Siemens. Square D homeline fits a Siemens, but Siemens doesn't fit a Homeline. Cutler Hammer makes a breaker specifically to fit a Square D QO, so I guess it's listed.
Our trucks are stocked with a wide array of breakers so we don't mix and match unless it's an obsolete panel, like Challenger, then we use a Siemens.
I really would like a list of "legal" breaker cross referrences.
