A control variable used to start and stop operator-initiated interface tests. Most OBJECT IDENTIFIER values assigned to tests are defined elsewhere, in associ- ation with specific types of interface. However, this document assigns a value for a full-duplex loopback test, and defines the special meanings of the subject identifier:

noTest OBJECT IDENTIFIER ::= { 0 0 }

When the value noTest is written to this object, no action is taken unless a test is in progress, in which case the test is aborted. Writing any other value to this object is only valid when no test is currently in progress, in which case the indicated test is initiated. Note that noTest is a syntactically valid object identifier, and any conformant implementation of ASN.1 and BER must be able to generate and recognize this value. When read, this object always returns the most recent value that ifExtnsTestType was set to. If it has not been set since the last initialization of the network management subsystem on the agent, a value of noTest is returned.