receiversSpecifier

If you create a subclass of NSScriptCommand, you don’t necessarily need to override this method, though some of Cocoa’s subclasses do. An override should perform the same function as the superclass method, with a critical difference: it causes the container specifier part of the passed-in object specifier to become the receiver specifier of the command, and the key part of the passed-in object specifier to become the key specifier. In an override, for example, if receiversRef is a specifier for the third rectangle of the first document, the receiver specifier is the first document while the key specifier is the third rectangle.