The description here is just a placeholder period, but the object name and enumeration make its purpose clear: this triggers a one-time database synchronization between the IDC, the indoor unit controller, and a drawer module, in one direction or the other, rather than reporting a continuous state. This is almost certainly used after replacing a drawer or IDC card to push the authoritative configuration from whichever side holds the current data onto the side that was just swapped. A technician who just replaced a failed drawer would set this to idcToDrawer(3) to push the IDC's known-good configuration down to the freshly installed hardware.