This key identifies the originator of the error, which is either the NSNetService object or the mach network layer. For most errors, you should not need the value provided by this key.
Available in Mac OS X v10.2 and later.
Declaration Syntax Version Information- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)