The param command displays the parameter form paramname on the screen and allows input into data entry fields that assign values to menu variables. Paramname names a parameter form defined in the current menufile.
When a parameter form is defined for a menu choice using menudef, the param command is the first command in the group of commands for a choice. Menu recognizes the param command when it is the first command in a command group. If built-in menu commands are enabled, any command in the command group may use the param command. (Note: menudef restricts the use of the param command. When a parameter form is defined for a menu choice, a param command is assigned internally as the first command for the choice.)
For a detailed description of the format for a parameter form in a menufile, see section 8.7.