Month and day markers
Definition
- Month marker (月建): the branch of the solar month the cast falls in — Si month, Wu month, and so on.
- Day marker (日辰): the day's stem-branch pair, e.g. Bing-Shen day.
Liu Yao treats both as external time references: every line in the hexagram is measured against them. "The same hexagram cast yesterday and today" is therefore not the same reading.
Two places it goes wrong
One: months turn at the solar term, not at the lunar new moon. The month branch is the term month — Yin month begins at Start of Spring. Using the lunar month for it shifts everything by one term.
Two: the day marker is a continuous stem-branch count. The sixty-day cycle runs unbroken across months and years; it is not re-derived from the lunar calendar.
Use
- Fix the month branch from the moment of the cast.
- Convert the calendar date to a continuous sexagenary day to get the day marker and day stem.
- The day stem sets the starting point for the six spirits.
- Measure the useful spirit and any moving line against both markers; relatives and Shi/Ying are covered in their own entries.
Boundaries
- The markers supply reference, not verdicts.
- Solar-term instants have finite precision. When a cast lands near a term boundary the month branch can flip, so check the term time first.