+extern Rational DOUBLE_FLAT_ALTERATION;
+extern Rational THREE_Q_FLAT_ALTERATION;
+extern Rational FLAT_ALTERATION;
+extern Rational SEMI_FLAT_ALTERATION;
+extern Rational NATURAL_ALTERATION;
+extern Rational SEMI_SHARP_ALTERATION;
+extern Rational SHARP_ALTERATION;
+extern Rational THREE_Q_SHARP_ALTERATION;
+extern Rational DOUBLE_SHARP_ALTERATION;
+
+SCM ly_pitch_diff (SCM pitch, SCM root);
+SCM ly_pitch_transpose (SCM p, SCM delta);
+DECLARE_UNSMOB (Pitch, pitch);
+