it can't parse cron string with '?'

[Colin Chang]

when I try to parse a cron expression with '?' like 0 0 16 ? * SUN-THU, I got an error message bellow:

NCrontab.CrontabException: '?' is not a valid [Day] crontab field value. It must be a numeric value between 1 and 31 (all inclusive)

[Atif Aziz]

NCrontab does not support non-standard characters and extensions like ?. The Crontab Expression page describes the supported syntax.

I am closing this as by-design.