An old birth certificate may record clock time without explaining daylight saving rules. Before creating a Zi Wei Dou Shu chart, confirm the birthplace, date, legal time zone, and the source of the record rather than adding or subtracting an hour by assumption.
Build the evidence chain
Identify the place, date, legal time and daylight saving rules, and whether the record comes from a hospital, registry, or family memory, marking each source's reliability. Keep family recollections separate from documents. Time settings change the chart mainly when they cross a two-hour palace boundary; a birth in the middle of a period usually needs no adjustment for a few minutes.
Check how the app handles historical time
Confirm whether the chart software applies historical daylight saving automatically or requires standard time, and record the settings so the result can be reproduced. Preserve the original data before comparing candidate charts; the evidence remains the original document and the historical time rules.