EXAMPLE:

B
PUCC
ML
T17

The first line of the ANSCR class number represents the category of the work

B - Opera

The second line is the first four letters of a name or word

PUCC - Puccini

The third line is the first letter of the first three keywords in the tile or, if  one word, the first three letters of that word

ML - Manon Lescault

The fourth line is the first letter of the performer's name, followed by two digits of the commercial recording number 

  T-Tebaldi 17-London 1317

 The London Records recording of Tebaldi singing Puccini's Manon Lescault
 

B
PUCC
ML
T17

B - Operas

C - Choral Music

D - Vocal Music

E - Orchestral Music:

EA-General Orchestral, EB-Ballet, EC-Concertos, ES-Symphonies

F - Chamber Music

G - Solo Instrumental Music:

GG-Guitar, GO-Organ, GP-Piano, GS-Stringed Instruments

GV-Violin, GW-Wind Instruments, GX-Percussion Instruments

H - Band Music

J - Electronic Music

K - Musicals

L - Soundtrack Music: Movies and Television

M - Popular Music:

MA-Pop/Rock, MB-Blues, MC-Country,
MG-Gospel,MJ-Jazz, MN-New Age

P - National Folk and Ethnic Music

Q - International Folk and Ethnic Music

R - Holiday Music

S - Variety and Humor: Comic Monologues, Musical Satire, Radio Shows

T - Plays

U - Poetry

V - Prose

W - Documentaries

X - Instructional: Dictation, Languages, "How To..."

Y - Sound Effects

Z - Children's Recordings

ZI-Instructional, ZM-Music, ZS-Spoken