Regex Tester & Validator

This regex captures the year, month, day, and time components from an ISO 8601 formatted date-time string. It specifically looks for a 'T' separating the date and time, followed by a sequence matching the HH:MM:SS time format, and ignores any trailing characters like milliseconds or timezone offsets. It is commonly used to parse and rearrange datetime values for systems like openHAB 2.