How to read this operator declaration and implementation?
===

The code in question:

    struct PCArea {
            PCArea(
                int minxx = 0, 
                int minyy = 0, 
                int maxxx = 0, 
                int maxyy = 0
            ) {}
        };
    
    struct NDCVolume {
        NDCVolume() {}
    
        operator PCArea() const;
    };
    
    // how does this operator work? how to use/read it?
    NDCVolume ::operator PCArea() const {
    
        return PCArea(iminx, iminy, imaxx, imaxy); 
    }

Redundant code has been removed from the snippet. I have used Visual Studio > Find All References but cannot spot any where it is being used. To me, it looks like a member method without a specified return value.

How is this different from below?

    PCArea NDCVolume::PCArea() const;