Are there any graphical / text-based user interface calendar programs which use the UNIX calendar utility format to store entries?

On some UNIX systems, there is a calendar utility which acts as a reminder service and which reads entries from files specified in tab-separated format, e.g.: 01/01\tNew Year's Day 01/02\tBank holiday in Scotland 01/25\tBurns' Night in Scotland 02/14\tSaint Valentine's Day 03/01\tSaint David's Day in Wales 03/17\tSaint Patrick's Day in Northern Ireland (also a bank holiday there) Are there any graphical or text-based user interface calendar programs which support this format?