In modern musical notation and tuning, an enharmonic equivalent is a note (enharmonic tone) interval (enharmonic interval) or key signature (enharmonic key signature) which is equivalent to some other note, interval, or key signature but "spelled", or named differently (enharmonic relation). Thus, the enharmonic spelling of a written note, interval or chord is an enharmonic equivalent to the way that note, interval or chord would be written under the current key signature. In other words, if two notes have the same pitch but are represented by different letter names and accidentals, they are enharmonic. Enharmonic equivalence is not to be confused with octave equivalence, nor are enharmonic intervals to be confused with inverted or compound intervals. "Enharmonic equivalents are tones that have the same pitch but different letter names....Two tones having the same pitch but different spelling". "Enharmonic intervals are intervals with the same sound that are spelled differently...[resulting], of course, from enharmonic tones." Prior to this modern meaning, "enharmonic" referred to relations in which (using traditional notation) there is no exact equivalence between a sharpened note and the flattened note., as in enharmonic scale.