This attribute records the results of the clock source test, indexed by the clock source and the slot number of the card containing the bus tap tested. Each entry contains one of the following values. +: the bus tap was able to receive clock signals from the clock source X: the bus tap was unable to receive clock signals from the clock source .: the bus tap was not tested against the clock source The bus test terminates automatically if a failure is detected involving the active control processor (CP) clock source.