This read-write object's only defined value is int10MHz(0), selecting the unit's internal 10 MHz reference as the frequency reference source. Unlike the CDM-570's richer set of external reference options, this CDD-564 object exposes only the internal reference, meaning frequency accuracy and stability for this unit are tied entirely to its own internal oscillator rather than an external, potentially more precise, site reference. A network requiring tight frequency synchronization across multiple sites would need to rely on other means since this object provides no path to lock the CDD-564 to a shared external house reference.