Error 0x8051000A

Value: -2142175222 | 0x8051000A | 2152792074

What does it mean ?

OPC_E_INVALID_RELS_XML  
The relationship markup for a Relationships part is not well-formed XML.
Value: 10 | 0x000A | 0b0000000000001010

Where does it come from ?

FACILITY_OPC  
Open Connectivity Service (Package Consumption)
Value: 81 | 0x051 | 0b01010001

Other Errors for FACILITY_OPC