Variable PLAIN_DATE_TIME_PATTERN`Const`

PLAIN_DATE_TIME_PATTERN: "^\\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\\d|3[01])T([01]\\d|2[0-3]):[0-5]\\d(:[0-5]\\d(\\.\\d{1,9})?)?$"

Regex pattern for Temporal.PlainDateTime ISO 8601 strings (e.g. 2023-01-15T13:45:30). Validates month (01–12), day (01–31), hours (00–23), minutes/seconds (00–59), and up to 9 fractional digits. No timezone offset.