Seven characters do paste

These seven are in the Miscellaneous Symbols block, they encode in three bytes of UTF-8, and they survive a paste into a form field, a filename or a database row.

Character	Codepoint	Unicode name	What it draws
♩	U+2669	QUARTER NOTE	one note, no flag
♪	U+266A	EIGHTH NOTE	one note, one flag
♫	U+266B	BEAMED EIGHTH NOTES	two notes, one beam
♬	U+266C	BEAMED SIXTEENTH NOTES	two notes, two beams
♭	U+266D	MUSIC FLAT SIGN	lowers a note a semitone
♮	U+266E	MUSIC NATURAL SIGN	cancels a sharp or flat
♯	U+266F	MUSIC SHARP SIGN	raises a note a semitone

Four of them are broken out on music note symbols and three on sharp and flat symbols. That is the entire music repertoire below U+FFFF: no clef, no rest, no time signature, no dynamic.

The block that holds everything else

Unicode does encode the rest of Western notation. The Musical Symbols block runs from U+1D100 to U+1D1FF, 256 slots of which 233 are assigned: every clef, every rest, note heads, barlines, repeat signs, dynamics, ornaments, pedal marks, and mensural and Kievan notation on top. It is a thorough job, and every character in it is unusable anywhere that will not take four bytes, for a reason that has nothing to do with music.

Three bytes against four

In UTF-8 a character's byte length follows its codepoint. Everything up to U+FFFF fits in one, two or three bytes. Everything above U+FFFF needs four. ♩ QUARTER NOTE is three bytes; U+1D15F MUSICAL SYMBOL QUARTER NOTE, which draws the same thing, is four.

That boundary is load-bearing because a store or a field can be built to accept a maximum of three bytes per character and still call itself UTF-8. Send a four-byte character to one and it is refused, or the text is cut at that point and everything after it is lost. Nothing warns you at the keyboard; the character looks fine until it is written down.

UTF-16 draws the line differently. Above U+FFFF a character becomes a surrogate pair, two code units instead of one, so anything counting a length in UTF-16 units counts a clef as two. A truncation that cuts at an arbitrary unit can slice the pair in half and leave a broken half-character.

Fonts are a separate problem on top of encoding: bytes can arrive intact and still show a box, if whatever is drawing the text has no glyph for that codepoint.

Thirty-eight of the 233 are not standalone characters

Even where the bytes arrive, not every slot is a mark you can drop into a line of text. Of the 233 assigned characters, 22 are non-spacing combining marks and 8 are spacing combining marks: they attach to the character before them rather than standing alone. A further 8, from U+1D173 MUSICAL SYMBOL BEGIN BEAM to U+1D17A MUSICAL SYMBOL END PHRASE, are format characters with no visible shape at all. The remaining 195 are ordinary symbols.

The notation characters, by codepoint

Names below come straight from the Unicode character database. There is no column of characters to copy, because wherever the four-byte limit bites there would be nothing to see. If your software takes a codepoint, this is the number to give it.

Codepoint	Unicode name	What it marks
U+1D100	MUSICAL SYMBOL SINGLE BARLINE	starts and separates bars
U+1D101	MUSICAL SYMBOL DOUBLE BARLINE	marks the end of a section
U+1D102	MUSICAL SYMBOL FINAL BARLINE	marks the end of the piece
U+1D106	MUSICAL SYMBOL LEFT REPEAT SIGN	opens a repeated passage
U+1D107	MUSICAL SYMBOL RIGHT REPEAT SIGN	closes a repeated passage
U+1D109	MUSICAL SYMBOL DAL SEGNO	jump back to the segno
U+1D10A	MUSICAL SYMBOL DA CAPO	jump back to the start
U+1D10B	MUSICAL SYMBOL SEGNO	the point a dal segno returns to
U+1D10C	MUSICAL SYMBOL CODA	the tail section jumped to at the end
U+1D110	MUSICAL SYMBOL FERMATA	hold the note beyond its written length
U+1D11E	MUSICAL SYMBOL G CLEF	the treble clef
U+1D121	MUSICAL SYMBOL C CLEF	the alto and tenor clef
U+1D122	MUSICAL SYMBOL F CLEF	the bass clef
U+1D129	MUSICAL SYMBOL MULTIPLE MEASURE REST	one sign standing for several silent bars
U+1D12A	MUSICAL SYMBOL DOUBLE SHARP	raises a note two semitones
U+1D12B	MUSICAL SYMBOL DOUBLE FLAT	lowers a note two semitones
U+1D134	MUSICAL SYMBOL COMMON TIME	the C-shaped four-four time signature
U+1D135	MUSICAL SYMBOL CUT TIME	the struck C, two-two time
U+1D13B	MUSICAL SYMBOL WHOLE REST	silence for a whole bar
U+1D13C	MUSICAL SYMBOL HALF REST	silence for two beats in four-four
U+1D13D	MUSICAL SYMBOL QUARTER REST	silence for one beat in four-four
U+1D13E	MUSICAL SYMBOL EIGHTH REST	silence for half a beat
U+1D13F	MUSICAL SYMBOL SIXTEENTH REST	silence for a quarter of a beat
U+1D15C	MUSICAL SYMBOL BREVE	the double whole note
U+1D15D	MUSICAL SYMBOL WHOLE NOTE	four beats in four-four
U+1D15E	MUSICAL SYMBOL HALF NOTE	two beats in four-four
U+1D15F	MUSICAL SYMBOL QUARTER NOTE	one beat in four-four
U+1D160	MUSICAL SYMBOL EIGHTH NOTE	half a beat
U+1D18F	MUSICAL SYMBOL PIANO	the p in dynamics
U+1D190	MUSICAL SYMBOL MEZZO	the m in mp and mf
U+1D191	MUSICAL SYMBOL FORTE	the f in dynamics
U+1D192	MUSICAL SYMBOL CRESCENDO	the opening hairpin, get louder
U+1D193	MUSICAL SYMBOL DECRESCENDO	the closing hairpin, get quieter
U+1D196	MUSICAL SYMBOL TR	the trill mark
U+1D1AE	MUSICAL SYMBOL PEDAL MARK	put the sustain pedal down
U+1D1AF	MUSICAL SYMBOL PEDAL UP MARK	lift the sustain pedal

Chord symbols are built from ordinary characters

A chord symbol is not one character. C♭m7 is a letter, a sign, a letter and a digit. Beyond the accidentals, the marks that are not letters are the ring of the diminished chord, typed as ° U+00B0 DEGREE SIGN; the slashed o of the half-diminished, typed as ø U+00F8 LATIN SMALL LETTER O WITH STROKE; and the triangle of the major seventh, typed as Δ U+0394 GREEK CAPITAL LETTER DELTA. All are below U+FFFF, so a chord chart written this way pastes whole.

What to use instead

For a clef or a rest in running text, a picture of the notation is the only thing that looks the same everywhere it lands. For note values, accidentals and chord names, use the seven above and stay below U+FFFF. Music symbols indexes the rest of this wing.