A birth-chart form looks simple: ask for a date, time, and place, then calculate. The interface may be simple. The input is not. 1992-11-01 01:30 does not identify one universal instant. It is a wall-clock reading that only becomes meaningful after you resolve the place, the historical time-zone rule, and any daylight-saving transition. If the time is unknown, inventing a convenient default can create chart features that were never supported by the user’s data. I ran into these proble...