Oh !! I'm just thought that everything was the same (I called PCI, but thought today this is called PCIE)
The motherboard outline only shows PCI_E1, PCI_E2, PCI_E3, PCI_E4 and PCI_E5. And in that commented part, it is explained the point of M2_2 disabling PCI_E2 to PCI_E5)
Thanks.