HP ProCurve 6400cl Series Management And Configuration Manual page 243

Power Over Ethernet (PoE) Operation for the Series 5300xl Switches
Port < port-id > PD Invalid Signature indication.
The switch has detected a non-802.3af-compliant device on the
indicated port. This message appears for all non-802.3af devices
connected to the port, such as other switches, PC-NICs, etc.
Port < port-id > PD MPS Absent indication.
The switch no longer detects a device on < port-id >. The device may
have been disconnected, powered down, or stopped functioning.
Port < port-id > PD Other Fault indication.
There is a problem with the PD connected to the port.
Port < port-id > PD Over Current indication.
The PD connected to < port-id > has requested more than 15.4 watts
of power. This may indicate a short-circuit or other problem in
the PD.
PoE Operating Notes
11-25