Devices are needed to comply with a protocol so which the interrupt-ask for (IRQ) lines is usually shared. The PCI bus involves four interrupt traces, INTA# by INTD#, all of which are available to every device. As much as eight PCI units share the identical IRQ line (INTINA# via INTINH#) https://nathanlabsadvisory.com/eu-us-privacy-shield-gdpr/