the property is present in setting A
the property is present in
setting A but is set to the default value. This flag is only set,
if you specify NM_SETTING_COMPARE_FLAG_DIFF_RESULT_WITH_DEFAULT.
the property is present in setting B
analog to NM_SETTING_DIFF_RESULT_IN_A_DEFAULT.
unknown result
These values indicate the result of a setting difference operation.