Products are required to stick to a protocol so that the interrupt-request (IRQ) traces is often shared. The PCI bus features 4 interrupt lines, INTA# by way of INTD#, all of which are offered to every product. Nearly 8 PCI gadgets share the exact same IRQ line (INTINA# by INTINH#) https://nathanlabsadvisory.com/cybersecurity-technical-writing/