COM connection for ULN 2803

In the ULN 2803 Darlington Transistor Array, there is a pin known as COM (pin 10) where all diodes are connected to.

From the datasheet, i can only identify that these diodes are clamping diodes.

Should I connect this pin 10 to VCC or GND?
What is the purpose of the diodes attached to the collectors?

Help is very much appreciated=)

Hi,

Pin 10 should be connected to Vcc , it connects each diode across each relay to stop the emf from the relay coil.