PIC24F: RPINR0 register
From the PIC24FJ64GA004 Family Reference Manual


  10.4.3.1      Input Mapping
  The inputs of the Peripheral Pin Select options are
  mapped on the basis of the peripheral; that is, a control
  register associated with a peripheral dictates the pin it
  will be mapped to. The RPINRx registers are used to
  configure peripheral input mapping (see 
  Register 10-1
  through 
  Register 10-14
  ). Each register contains two
  sets of 5-bit fields, with each set associated with one of
  the pin-selectable peripherals. Programming a given
  peripheral’s bit field with an appropriate 5-bit value
  maps the RPn pin with that value to that peripheral. For
  any given device, the valid range of values for any of
  the bit fields corresponds to the maximum number of
  Peripheral Pin Selections supported by the device. 


RPINR0 is the input control register for External Interrupt 1 (INT 1).  PRINR0 is a 16 bit register, with bits 8 to 12 actually implemented.  Those 5 bits controls which pin can drive External Interrupt 1.  

Here's the register definition from the family reference manual.



The desired pin number gets written to the register.  For example, if I wanted to map RP1 to External Interrupt 1 (INT1), I would do this: 

RPINR0 = 0x0100.

This will assign the decimal value of 1 to the top byte of the RPINR0 of the special function register, which will map the RP1 pin to the External Interrupt 1 (INT1) module.

Assuming INT1 is configured correctly in your case, when some external device wiggles RP10, the hardware will trigger the INT1 interrupt, at which point the firmware can decide what to do with it through an interrupt service routine.