does PACII really act like a PAC tranch or it is more like a support tranche? Thanks.
Not exactly my field of expertise, but I thought that PAC II tranches were created from the cash flows to the support tranche for the PAC I. That is, there are two tranches active at one time: the PAC I and its support tranche. Then once money goes to the support tranche there are two tranches active: the PAC II and its support. That means a PAC II acts like a PAC except that it is part of support so the answer to your question is something like “both”.
I agree w/ JDV. Plenty of examples in the EOC’s of this.