32 characters in the Modifier Tone Letters Unicode block.
U+A700MODIFIER LETTER CHINESE TONE YIN PINGU+A701MODIFIER LETTER CHINESE TONE YANG PINGU+A702MODIFIER LETTER CHINESE TONE YIN SHANGU+A703MODIFIER LETTER CHINESE TONE YANG SHANGU+A704MODIFIER LETTER CHINESE TONE YIN QUU+A705MODIFIER LETTER CHINESE TONE YANG QUU+A706MODIFIER LETTER CHINESE TONE YIN RUU+A707MODIFIER LETTER CHINESE TONE YANG RUU+A708MODIFIER LETTER EXTRA-HIGH DOTTED TONE BARU+A709MODIFIER LETTER HIGH DOTTED TONE BARU+A70AMODIFIER LETTER MID DOTTED TONE BARU+A70BMODIFIER LETTER LOW DOTTED TONE BARU+A70CMODIFIER LETTER EXTRA-LOW DOTTED TONE BARU+A70DMODIFIER LETTER EXTRA-HIGH DOTTED LEFT-STEM TONE BARU+A70EMODIFIER LETTER HIGH DOTTED LEFT-STEM TONE BARU+A70FMODIFIER LETTER MID DOTTED LEFT-STEM TONE BARU+A710MODIFIER LETTER LOW DOTTED LEFT-STEM TONE BARU+A711MODIFIER LETTER EXTRA-LOW DOTTED LEFT-STEM TONE BARU+A712MODIFIER LETTER EXTRA-HIGH LEFT-STEM TONE BARU+A713MODIFIER LETTER HIGH LEFT-STEM TONE BARU+A714MODIFIER LETTER MID LEFT-STEM TONE BARU+A715MODIFIER LETTER LOW LEFT-STEM TONE BARU+A716MODIFIER LETTER EXTRA-LOW LEFT-STEM TONE BARU+A717MODIFIER LETTER DOT VERTICAL BARU+A718MODIFIER LETTER DOT SLASHU+A719MODIFIER LETTER DOT HORIZONTAL BARU+A71AMODIFIER LETTER LOWER RIGHT CORNER ANGLEU+A71BMODIFIER LETTER RAISED UP ARROWU+A71CMODIFIER LETTER RAISED DOWN ARROWU+A71DMODIFIER LETTER RAISED EXCLAMATION MARKU+A71EMODIFIER LETTER RAISED INVERTED EXCLAMATION MARKU+A71FMODIFIER LETTER LOW INVERTED EXCLAMATION MARK