PdfDate
data class PdfDate(val year: Int, val month: Int, val day: Int, val hour: Int, val minute: Int, val second: Int, val tzSign: Char, val tzHour: Int, val tzMinute: Int)
A PDF date-time (ISO 32000-1 §7.9.4): D:YYYYMMDDHHmmSSOHH'mm'.
Each component except year is optional; missing tail bytes default to the smallest sensible value (1 for month/day, 0 otherwise). The D: prefix is also optional in practice (writers occasionally omit it).
tzSign is one of '+', '-', 'Z'. 'Z' means UTC and forces the hour/minute offsets to zero.