Devices are needed to follow a protocol so that the interrupt-request (IRQ) lines can be shared. The PCI bus involves 4 interrupt strains, INTA# by means of INTD#, all of which are available to every device. As many as 8 PCI units share the identical IRQ line (INTINA# through INTINH#) https://nathanlabsadvisory.com/eu-us-privacy-shield-gdpr/