Error 0x8051002F

Value: -2142175185 | 0x8051002F | 2152792111

What does it mean ?

OPC_E_DS_EXTERNAL_SIGNATURE_REFERENCE  
A Reference element in the signature markup refers to an object that is external to the package. Reference elements must point to parts or Object elements that are internal.
Value: 47 | 0x002F | 0b0000000000101111

Where does it come from ?

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

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