Forms Reports Question:

The Restrict List to Predetermined Values is a checkbox
that indicates whether a value for the parameter must be in
the list of values. For example, if you check Restrict
List to Predetermined Values and the Initial Value does not
match a value in the list of values, an error will be
generated when you accept the Parameter property sheet.
Similarly, if you set a value for the parameter on the
command line or in a command script and it does not match a
value in the list of values, an error will be generated
when the report is run. If you check Restrict List to
Predetermined Values, a list of values will appear in the
runtime parameter form. If you do not check it, a combo
box will appear (i.e., you can enter values as well as
select from the list).