## Constrain Execution to a Single File

Actions will not execute without at least one selected audio file. It is possible to write an action which does not actually require any audio files. For example, an action which manipulates a query database file and dynamically loads any required files if necessary. It may be somewhat of a pain in these actions to safely ignore any files which might have been selected, especially when running an action or sub-action as grouped.

This statement effectively forces the action to operate on a single file only. This means that you can execute stepwise or grouped and not have to worry about multiple executions of an action, regardless as to how many files are selected.

The statement is ignored if one has already been executed and is not valid while running grouped.

Note that the statement will not have the desired effect if executed in an action (or sub-action) called by a Load and Run statement.

Once this statement is executed, there is no going back. You cannot return to processing all selected files. However, the Run, Repeat With and Test statements all support a Grouped-Once mode which effectively does the same as this statement for a single run of an action.