Didn't we used to have a documentation section?
Anyway I'm looking at the Mega schematics and documentation and can't seem to match the two, for example interrupt 0 is on DIG2 according to the docs but digital 2 goes to INT4 on the chip, the others are different as well, as follows
2 (interrupt 0) INT4, pin 6 on chip 3 (interrupt 1) INT5, pin 7 21 (interrupt 2) INT0, pin 43 20 (interrupt 3) INT1, pin 44 19 (interrupt 4) INT2, pin 45 18 (interrupt 5) INT3, pin 46
So is something wrong or are the Arduino "interrupts" just logical numbers that map to a different real interrupt?
Also digital 0 and 1 (Rx0 and Tx0) are shown as PWM on the schematic, presumably this just means that you can do a digitalWrite() as there's no hardware PWM support on these pins.