The Edit Constant dialog allows editing the type and value of a constant function:

The type is selected from a drop-down box and is a primitive type (int, long, ulong, string, byte, bool etc).
The value is required to be of the Result Types specified in the pull-down menu.
Note: Enter dates in YYYY-MM-DD format. For example, for January 7 2001 enter 2001-01-07.