This object indicates whether the currently-selected T0 clock source resulted from a manual switch command rather than fully automatic selection, a softer intervention than a forced switch, since per the description a manual switch can only be issued to a source that is enabled, not locked out, not failed, and, in QL-enabled mode, among those with the best available quality level. It matters because it tells an admin the current source was deliberately chosen by an operator working within the normal quality constraints, as opposed to either fully automatic selection or an override that ignores quality entirely. Distinguishing a true here, a constrained manual choice, from cnsSelInpSrcFSW being true, an unconstrained forced override, tells the admin how much operator discretion, versus emergency override, is behind the current clock selection.