The following coding scheme tables explain the relations between the date part (yyyy...) of a resource file line and the modifiers, the short-style option -c|C —which is used for enabling the fixed date feature— respectively the --period-of-fixed-dates=argument long-style option may have, i.e. they point out all possible correspondences. This is necessary because Gcal does not respect all entries found in a resource file if a fixed date argument is given, it respects only those entries which have a definite relation to the fixed date argument to avoid the output of redundant information! See Fixed dates option --period-of-fixed-dates=argument, for further details.
In the date part yyyy...:
99) respectively any textual short month name with length of 3 characters (