Hello Richard;
you just need to use the "Create Calendar" option. The "Update" option allows only to change the settings of a day (working / closed / holiday).
So just choose the "Create" Option, choose the Calendar (whether General, MU specific, template or MU type specific) and select the range of years you want to add, the typical week mask and the holidays management. The Calendar will be expanded.
It is also posible to do this in command mode - useful if you have many Calendars to update, you can create a little script.
The command is "uxadd CAL ... " (see the command manual for the various options).
To work on the General Calendar in command mode, you'll have to specify the internal MU " 00" (space zero zero).
Michel