aeiouHolidays are undefined but used by some Templates
If you think this message is appearing erroneously, make sure that it is not caused by one or more of the a-e-i-o-u sets being selected in the Holidays Override property of one of the DiaryGridLines.
Consequences : None of the holidays tokens corresponding to that Holidays List will be replaced. If you are doing a test run, this can be acceptable, but for the final diary, you need to correct this message.
This message usually appears in pairs, once as a message generated by one of the a-e-i-o-u Holidays Lists, and once as a message generated by the Template property of one of the DiaryGridLines (that message is the one which refers to the template by name).
•Change List of Holidays Sets : Opens the corresponding Holidays List property editor, so you can select one or more Holidays Sets to use.
•Edit Holidays Rules : Let you add/modify holidays rules.
•Select a Holidays Set : This opens up a sub-menu containing all the Holidays Sets of your shared database. You can then select one Holidays Set to associate with the current Holidays List. See also the next solution.
•Use one of the prefered Holidays Sets : At the bottom of this popup menu, you will find the "favourite" Holidays Sets as you have selected them in International Preferences. Note that you can only select one Holidays Set using this solution.