Devices are required to comply with a protocol so the interrupt-request (IRQ) traces could be shared. The PCI bus contains four interrupt traces, INTA# through INTD#, all of which are available to every gadget. As much as 8 PCI units share the exact same IRQ line (INTINA# via INTINH#) in https://nathanlabsadvisory.com/how-nist-800-171-compliance-consulting-in-usa-can-secure-your-business-data/