Units are required to comply with a protocol so which the interrupt-request (IRQ) traces can be shared. The PCI bus features 4 interrupt lines, INTA# via INTD#, all of which are available to each product. Nearly eight PCI products share the identical IRQ line (INTINA# as a result of INTINH#) https://nathanlabsadvisory.com/aramco-cyber-security-compliance/