Such considerations are important for hierarchically structured time server structures. The stratum level “0” always refers to the time server on the top level, which functions as the reference time source of the overall system, for example, by means of exact DCF / GPS synchronization. The level below, along with the time servers located there – which in turn synchronize themselves to level “0” – is given the stratum level “1” accordingly. Levels further below therefore add up the stratum level “n + 1”. As a rule, a maximum of 16 stratum levels are defined.