Space data and information transfer systems -- Time code formats
Time codes are digital representations of time information. ISO 11104:2011 describes four standard recommended time codes (one unsegmented and three segmented codes) which use the international standard second as the fundamental unit of time. An unsegmented time code is a pure binary count of time units and fractional time units from a starting time called the epoch. A segmented time code is one in which the count of time units and fractional time units is accumulated in two or more cascaded counters which count modulo of various bases and start from the epoch.