This module implements ISO 8601 date, time and duration parsing. The implementation follows ISO8601:2004 standard, and implements only date/time representations mentioned in the standard. If something is not mentioned there, then it is treated as non existent, and not as an allowed option. As this module maps ISO 8601 dates/times to standard Python data types, like date, time, datetime and timedelta, it is not possible to convert all possible ISO 8601 dates/times. For instance, dates before 0001-01-01 are not allowed by the Python date and datetime classes. Additionally fractional seconds are limited to microseconds. That means if the parser finds for instance nanoseconds it will round it to microseconds.