In each of the bottom three places on the circle of fifths the two enharmonic equivalents can be notated and so do not classify as ` theoretical keys ' : But when a relative key ascends the opposite side of the circle from its home key , then theory suggests that double-sharps and double-flats would have to be incorporated into the notated key signature .
In each of the bottom three places on the circle of fifths the two enharmonic equivalents can both be written without double-sharps or double-flats and so do not classify as ` theoretical keys ' : But when a relative key is on the opposite side of the circle from its home key , then in theory modulating to that key would involve adding so many sharps or flats that double-sharps and double-flats would have to be written in the key signature .