To run a query, select Query ... from the Eval menu to get the Query
dialog. The Enter a query field is for you to enter your query and the
Solutions field is used to return the instantiation values of the variables in the
query. The pointer changes from an arrow cursor to an I-beam within the query field.
If an existing query needs updating, position the I-beam at the place where the insertion
is required and click the mouse. MacProlog32 remembers the last evaluated query,
so that the command Run last query from the Eval menu can be used,
avoiding retyping.
If the All button is clicked, all the solutions to the query, together with the
original query, will appear in the Solutions field. The First option
displays the first solution and the Query dialog changes to display this solution as well.
Other solutions are found by clicking the Next button consecutively. The
Finish button will terminate the querying process.
There are three check boxes in the Query dialog. The Echo output box
enables the query to be echoed and the answers to be displayed in the 
Output
Window. The Compile box determines whether re-compilation should take place before
running a query; select it when you are, for instance, debugging a program so that
re-compilation is automatically done before the query is executed. The Hold dialog
box allows the Query dialog to remain open after the query finishes.