Calculated first. Interpreted second.

An inspectable BaZi chart.

Birth Pattern accepts a Gregorian date, a local civil time when known, a birthplace label, and an IANA time zone. The selected zone supplies the historical clock and daylight-saving rules used for the calculation.

• Gregorian birth date and recorded civil clock time
• An IANA birthplace time zone, including its daylight-saving rules
• Year, month, and day pillars
• An hour pillar when a reliable birth time is available
• Day Master element and polarity
• Visible occurrences of the five elements in the included stems and branches
• Hidden stems from the fixed branch table, including their Ten Gods
• Ten Gods for each known visible stem relative to the Day Master
• A separate unweighted register of visible and hidden stems
• Luck Pillars, onset ranges when needed, and the annual pillar at a saved reference date
• Optional longitude-only mean solar time, apparent True Solar Time, and a 23:00 day boundary
• Named stem and branch relations, with partial groups distinguished from complete membership

Known facts stay visible. Missing facts stay open.

YAO shows the stems and branches that the current engine can verify. Each included visible stem and branch contributes one occurrence to the element view. A known time normally gives eight visible symbols; an unknown time leaves the hour open and gives a smaller view.

The free chart includes its Hidden Stems and Ten Gods, plus Luck Pillars when the known birth year and month support them. A traditional sex category is optional and used only for direction; if absent, both alternatives are shown. Unknown birth time yields a range of possible luck changeovers across every permitted minute of the local birth day, including DST overlaps. No birth hour is invented.

Clock time stays visible in the policy.

The default remains recorded local civil time, with a midnight day boundary (sect 2). From 23:00 to 23:59, the library retains that day pillar but derives the Zi-hour stem from the following day. The optional 23:00 profile (sect 1) advances the Day pillar too; the Hour pillar follows the same library rule in both profiles. Neither school is silently substituted for another.

Mean solar time applies longitude × 4 minutes minus the resolved UTC offset in minutes. Apparent True Solar Time adds the NOAA/Meeus equation of time evaluated at the physical birth instant, then rounds the working clock to the nearest second. The historical offset already includes DST: it is not subtracted a second time. Longitude must be explicitly supplied; it is never inferred from a city label. This approximation does not establish exact astronomical accuracy near a day or hour boundary.

Only Day and Hour use the corrected working clock. Year, Month and luck onset keep the original physical instant. Solar-term comparisons use the library’s fixed UTC+08 reference. Li Chun sets the year; the twelve Jie set the month. Unknown birth time keeps the original civil-midnight partial chart: solar corrections and a 23:00 boundary can leave more than one possible Day Master and are not assigned without a time.

When a recorded moment is within 15 minutes of a solar-term boundary, the affected year or month pillar is left uncertain instead of being guessed. With an unknown birth time on a boundary day, YAO cannot choose between the possible pillars. A daylight-saving gap is rejected, and a repeated clock time stays uncertain unless the birth record identifies the occurrence.

Da Yun uses lunar-javascript 1.7.7 getYun(category, 2): Yang male / Yin female forward, the other two combinations backward. The real birth instant is converted to fixed UTC+08 before measuring to the adjacent Jie. Under this minute-based start-of-luck method, 4,320 minutes become one year, 360 one month, 12 one day, and the remaining minutes become two hours each. This is separate from day-boundary sect 2. Cycle anniversaries use the computed start date, not January 1. Results show the UTC+08 reference and preserve uncertainty.

Visible count means visible count.

“Wood 4 of 8” means four of the eight included visible symbols map to Wood. The second register expands known branches into Hidden stems, then counts each visible and hidden stem once. It never counts both a branch and its hidden content in the same register. It is an occurrence count, not a weighted measure of strength, balance, health, ability, or personality. An absent element is not a deficiency, and a higher count does not replace the Day Master reference.

The same facts, given more room.

Personal Reading validates the calculated snapshot and applies authored interpretation rules to Day Master, Four Pillars, Hidden Stems, Ten Gods, the two element registers, current Luck Pillars and the annual pillar. Its sections answer user questions about these relationships. Every interpretation block keeps a rule ID and the fact keys it uses. The report is deterministic for the same verified Birth Pattern, with no runtime AI-generated chart.

The original chart is Chart 0.3.0; explicit method-option snapshots use Chart 0.3.1. Both use the separately approved Reading Rules v0.3.2. New clock choices select different chart facts under the same authored reading rules. Saved reports keep their original method, facts and reference date.

Boundaries are part of the method.

• Transformation verdicts, interaction priority, or seasonal weighting
• Day Master strength, Useful God, or favorable-element judgement
• Compatibility scores or deterministic event forecasts

YAO is a cultural and interpretive practice for reflection. It does not establish medical, financial, legal, or personal outcomes. Your experience and informed decisions remain the final context.