AMP is, and will always be, fuzzy on the issue.
I don't know about exchange-traded spreads, but they simply (with CQG) DO NOT support intra spreads on manual legs, as defined by the exchange. Even though their broker statements say otherwise. I believe this, because someone at AMP on the phone told me this, and their CS reps must know how their operation works.
It has been that single issue that has been stifling my trading all these years...Knowledge of that one single issue. In that the relief provided by the exchange simply does not exist in their SPAN calculations, and all open legs are counted as full margin in the last 5 minutes of trading, whether you fit the definition of an intra-spread or not. Tough cookies.
Makes me mad, but I try to deal with it.
Advantage, Rosenthal Collins, RJO know how to correctly margin spread traders intraday