If you enter something within []s in the Criteria row of the query
design grid, the user will be prompted accordingly, and whatever they
enter in response to the prompt will be used as a selection criteria on
that column. This is called a Parameter Query. If you mean that the
start date and end date criteria will be applied to the same field in
the query, maybe you need something like this...
Between [Start date...] And [End date...]
