KeyboardEvent.location - Web APIs
dom_key_location_numpad 3 the key was on the numeric keypad, or has a virtual key code that corresponds to the numeric keypad.
... note: when numlock is locked, gecko always returns dom_key_location_numpad for the keys on the numeric pad.
... otherwise, when numlock is unlocked and the keyboard actually has a numeric keypad, gecko always returns dom_key_location_numpad too.
...that is, it must not be dom_key_location_numpad.

nsIDOMWindowUtils
deprecated since gecko 38.0 key_flag_location_numpad 0x0080 location attrubute of the sending key event by sendkeyevent() returns keyboardevent.dom_key_location_numpad if this is specified to the aadditionalflags.

KeyboardEvent - Web APIs
dom_key_location_numpad 0x03 the key is located on the numeric keypad, or is a virtual key associated with the numeric keypad if there's more than one place the key could originate from.