A BaZi chart is built from four time markers: year, month, day, and hour. The hour is not decorative. It supplies a Heavenly Stem and an Earthly Branch, completing two of the chart's eight visible characters. Leaving it out creates an incomplete Four Pillars chart. Traditional Chinese hours divide the day into twelve two-hour periods. The Hong Kong Observatory lists Zi hour as 23:00 to 01:00, Chou as 01:00 to 03:00, and so on through Hai at 21:00 to 23:00. A birth close to one of these boundaries can move into a different hour branch when the underlying time conversion changes. The time written on a birth record is civil time. To use a method based on local solar time, a calculator must first resolve the historical time zone and any daylight-saving rule, then account for the birthplace longitude. Apparent solar time also differs from mean solar time through the equation of time, which changes during the year. Location therefore matters even when two places share the same official time zone. They can sit far apart in longitude, so the Sun crosses their local meridians at different clock times. The difference may be enough to change the hour pillar for a birth near a two-hour boundary. Day and year boundaries need equal care. Four Pillars schools can use different rules around the Zi hour and the start of a new day, and many BaZi methods use Li Chun rather than Lunar New Year as the year boundary. A responsible calculator states these conventions instead of hiding them behind a single result. Lore of Stars records the submitted civil time, coordinates, time-zone conversion, true solar date and time, and the boundary settings used by its BaZi engine. Keeping that calculation evidence with the chart makes disagreements easier to investigate and prevents an interpretation from concealing an input or convention mismatch. If the birth time is unknown, do not invent one. A partial chart can still show the year, month, and day pillars, but the missing hour should remain clearly marked and any interpretation that depends on it should be treated as uncertain. Precision begins with honest inputs, not a more confident description.