Products are required to abide by a protocol so which the interrupt-request (IRQ) strains is often shared. The PCI bus incorporates 4 interrupt traces, INTA# via INTD#, all of which are available to every device. Nearly eight PCI units share a similar IRQ line (INTINA# through INTINH#) in APIC-enabled x86 https://nathanlabsadvisory.com/iso-iec-19770-1-2017-it-asset-management/