Just planting a seed for your contemplation when working on Calendar features...

Items in the Calendar use Item-specific Properties to determine the display of the Item in the Calendar;  ItemColor for the Fill and ItemForeColor for the Text Color. On the other hand, the color of the BORDER around the Item is determined by the COLOR associated with the DATE Field linking the Item to the Calendar. To have 5 distinct Border Colors, there has to be 5 defined Date Fields and data entry requires the user to determine which Field gets the Date info.

Adding a Field Property like ItemBorderColor (which could DEFAULT to the Date Field Color to mimic the current behavior) would be a more flexible solution.