Online Documentation for SQL Manager for InterBase/Firebird
Specifying input parameters
If the stored procedure (or function) has parameters, the Input Parameter dialog appears before the execution. It allows you to specify the values for all parameters. After changes are done, click the OK button to execute the stored procedure\function, or the Cancel button to abort the execution.
Also you can choose the recently used set of values in the table at the top of the window. To apply values from the table just double-click its row.