Six Officers (Liù Yào) 六曜 Glossary

A lunar-month day label (先勝/友引/先負/仏滅/大安/赤口) — the one officer family in the almanac keyed to the lunar calendar, deliberately opposite to every other system on the page.

Liù Yào · 六曜 · liu yao · Rokuyō · 先勝 友引 先負 仏滅 大安 赤口 · 六曜 (Japanese)

Source credibility (S/A/B/C/X): B    Rule computability (A/B/C): A

What it is

Six day labels — 先勝, 友引, 先負, 仏滅, 大安, 赤口 — whose cycle runs on the lunar month and day, computed as (lunar month + lunar day) mod 6. That is structurally different from every other almanac officer, all of which key to the solar-term month; the two calendars drift apart by up to weeks within a year. The system is often called Rokuyō （六曜） in Japan, where it is widely printed on calendars.

School differences

Transmission variants exist around the starting point of the cycle and the treatment of leap months. The engine takes the common mainland/Japanese convention and labels it; where a source conflicts, the dispute register records the case.

How this engine computes it

• Because it needs the lunar month and day, the kernel requires explicit lunar inputs for this field — it never guesses the lunar calendar when the input is ambiguous. The almanac page computes it from the same lunar data shown on the page.
• Displayed beside the solar-term-keyed officers with a one-line note that the calendar basis differs — the page's whole design principle in miniature.

Related entries

Jian Chu · Yellow–Black Path · Daily almanac · School Dispute Register

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