Equipment are required to comply with a protocol so which the interrupt-request (IRQ) traces can be shared. The PCI bus incorporates 4 interrupt lines, INTA# by INTD#, all of which are available to each product. As much as eight PCI products share the identical IRQ line (INTINA# as a result https://nathanlabsadvisory.com/iot-testing-in-the-usa-protect-your-devices-from-cyber-threats/