At a glance
- Composition
- Four pairs, eight characters
- Inputs
- Date, time, place and conventions

Definition and terminology
Each pillar contains a stem and branch: four pairs make eight characters. They are not copied directly from lunar date numbers, and a zodiac animal is insufficient. Reliable date, recorded clock time, location and historical time-zone information define the input. Preserve those facts before comparing chart calculations or interpretations.
Structure and rules
Ziping practice commonly uses Start of Spring for the year and twelve solar-term boundaries for months, rather than lunar month beginnings. Day labels follow a continuous cycle; hour stems derive from day stems. Solar-time correction and day rollover vary. A chart should expose its conventions rather than conceal disagreements in defaults.
Worked reading
Suppose a teaching input has a verified Jia-Zi day and falls within Zi hour under the chosen convention. The hour-stem table gives Jia for Zi hour on a Jia day, yielding a Jia-Zi hour pillar. This checks one mapping only. Year and month require separate calculation, and boundary inputs may warrant alternative charts.
Context and limits
Sanming Tonghui documents natal rules without proving that birth timing determines life events. Recorded minutes may exceed the actual precision of historical records. Solar-term transitions and overseas daylight saving need checking. Explain the conversion process and uncertainty before presenting interpretations as school-specific opinions rather than facts about destiny.
References & further reading
Historical sources document ideas and rules of their time, not empirical proof of predictive accuracy. Source notes identify the nature and scope of each reference.
- 《三命通会》(四库全书本)Primary / tradition source
Public-domain natal-divination compilation with historical editorial criticism; rule documentation, not modern validation.
- Hong Kong Observatory: Heavenly Stems and Earthly BranchesInstitutional / reference source
Official calendar reference for sequences and double hours; does not validate natal divination.