[ CCode ( cname = "GDATA_GCONTACT_EXTERNAL_ID_CUSTOMER" ) ]
[ Version ( since = "0.7.0" ) ]
public const string GCONTACT_EXTERNAL_ID_CUSTOMER
The relation type URI for a customer identifier.
For more information, see the <ulink type="http" url="http://code.google.com/apis/contacts/docs/3.0/reference.html#gcExternalId"> gContact specification</ulink>.