By default, all software supports multiple file extensions. Apple Calendar (iCal) supports at least 8 different file extensions. The basic files that Apple Calendar (iCal) supports are .ICS. However, not all of the extensions listed on the list are always used to save the effects of work in Apple Calendar (iCal). Very often, files with such extensions are used as source data files used by Apple Calendar (iCal).
Apple Calendar (iCal) can be used to convert file formats between the file extensions listed below. You can open a file with one of the file extensions below via Apple Calendar (iCal) and try to save it in another file format, also supported by Apple Calendar (iCal).