* 仕様書

[REFS[
- [2] [[ISO 8601:2004]]
]REFS]

* 定義

[FIG[
[FIGCAPTION[
[1] [SRC[[[ISO 8601:2004]] 2.1.4]]
]FIGCAPTION]
> system of ordered marks which can be attributed to instants on the time axis, one instant being chosen as the
origin [SRC[IEC 60050-111]]
]FIG]