Chip identification

Hi, I was wandering what the extensio meant in the chip identification code:
Like the E/ML or the I/P ? thanks
k

PIC18F4685-E/ML 44 QFN -40C to +125C TUBE
PIC18F4685-E/P 40 PDIP -40C to +125C TUBE
PIC18F4685-E/PT 44 TQFP -40C to +125C TRAY
PIC18F4685-I/ML 44 QFN -40C to +85C TUBE
PIC18F4685-I/P 40 PDIP -40C to +85C TUBE
PIC18F4685-I/PREL 40 PDIP -40C to +85C TUBE
PIC18F4685-I/PT 44 TQFP -40C to +85C TRAY
PIC18F4685-I/PXXX 40 PDIP -40C to +85C TUBE
PIC18F4685T-I/ML 44 QFN -40C to +85C T/R
PIC18F4685T-I/PT

That was a copy and paste from the microchip web site