In the datasheet of the 18F4620 and others, section 9.0 (page 91), I read:
The PIC18F2525/2620/4525/4620 devices have multiple interrupt sources and an interrupt priority feature that allows most interrupt sources to be assigned a high priority level or a low priority level. The high priority interrupt vector is at 0008h and the low priority interrupt vector is at 0018h. High priority interrupt events will interrupt any low priority interrupts that may be in progress.
I see that when a low priority interrupt service routine is running and a high priority interrupt occurs, the high priority ISR will be runt.
However, what happens when a high priority interrupt occurs during a high priority ISR? Or, when a low priority interrupt occurs during a low priority ISR?