identifying left leading digits and symbols for removal (required for example for cleaning units of measure)

Regex able to parse iCal to fetch, for example, the schedule of students.

The regular expression checks for the street numbers or apartment numbers of addresses. It also assumes that the numbers can have a prefix or suffix. Unit/Apartment numbers are of the form Unit Number/Street Number e.g. 10/12.

This regex validates the year 1200-2299.