I was talking specifically about the ABC standard
created by Irwin Oppenheim, with which people
post tunes on this board. I assumed that’s what
the OP was asking about. As I mentioned in my
post, that standard is based on a much older
method of just writing the letter names of the
notes without any other (standardized) markup
or tags.
If the OP was asking about how to read that,
there’s not much helping them, so I was giving
them the benefit of the doubt.
And Oppenheim’s reason for creating the standard
was for ABC code to be translated into sheet music,
else there’d be no need for the header tags like X:
and L: If you wanted to show something purely for
humans to read, you would strip it of all the tags
that really are essentially programming tools. The
standard came about during Usenet times because
it was more efficient to send a few hundred bytes
of text which could be downloaded and run through
a translator to get sheet music GIF than to encode
and post the GIF itself.
This is less obvious for, say, ITM tunes, but look at
this ABC code I wrote for a madrigal. Not particularly
human readable:
X:1
T: Cadgwith Anthem
M:3/4
L:1/4
K:Eb
%%header $T (page $P)
%%measurenb 0
%%scale .7
%%staffsep 70pt
%%staves [1 2 3 4]
%SOPRANO
V:1 name=“Soprano” clef=treble
E/2G/2 | Be e/2d/2 | eBe | B/2c/2 BB | c/2B/2 G2- |
w: Come_ fill up your_ glass-es and let_ us be mer-*ry,
w: Hush,_ hush, in the_ dis-tance there’s foot-*steps ap-proa-*ching.
%5
Gz E/2G/2 | Be e/2d/2 | eB B/2e/2 | cBA | G3- |
w: _ For to rob bags of_ plun-der it_ is our in-tent.
w: _ Stand,_ stand and de-*li-ver, it_ is our watch cry.
%10
Gz F/2G/2 | A A/2B/2 A | G/2A/2 B2- | Bz A/2B/2 | ce e/2c/2 |
w: _ As we roam through_ the val-*ley,_ Where the li-lies and the
%15
B/2c/2 e2- | ez e/2c/2 | BBc | BcE | FBA | G3- |
w: ro-*ses,_ And the Beau-ty of Cash-mere lay droo-ping its head.
%21
Gz F/2G/2 |
w: _ Then a-
M:4/4
A3 G/2A/2 | B3 A/2B/2 |
w: way, then a-way, then a-
M:3/4
c/2B/2 A/2B/2 c/2A/2 | B3- |
w: way______
%26
Bz c/2c/2 | BB e/2e/2 | BG B/2e/2 | B/2c/2 BA | G3- | HG z 
w: _ To the caves in yon-der moun-tain where the rob-*bers re-treat._
%
%ALTO
V:2 name=“Alto” clef=treble
z | z3 | z3 | F/2E/2 D D/2F/2 | E E2- |
w: let_ us be_ mer-ry,
w: foot-*steps ap-*proa-ching.
%5
Ez (B,/2B,/2) | EDC | B,E E/2G/2 | FDB, | B,3- |
w: _ For to rob bags of plun-der it_ is our in-tent.
w: _ Stand,_ stand and de-li-ver, it_ is our watch cry.
%10
B,z B,/2B,/2 | DD C/2B,/2 | B, B,2- | B,z B,/2B,/2 | CE E/2F/2 |
w: _ As we roam through the_ val-ley,_ Where the li-lies and the
%15
E/2F/2 G2- | Gz G/2A/2 | GGE | EEE | D/2E/2 FD | E3- |
w: ro-*ses,_ And the Beau-ty of Cash-mere lay droo-*ping its head.
%21
Ezz |
w: _
M:4/4
z B,/2>B,/2 B,z | z E/2>E/2 E B,/2B,/2 |
w: then a-way, then a-way, then a-
M:3/4
B, C/2D/2 E/2F/2 | G3- |
w: way_____
%26
Gz F/2E/2 | GG G/2A/2 | G/2F/2 E E/2G/2 | F/2E/2 D D/2F/2 | E3- | HE z 
w: _ To the caves in yon-der moun-*tain where the rob-*bers re-*treat._
%
% TENOR
V:3 name=“Tenor” clef=bass
E,/2G,/2 | B,B,E | G,G,G, | B,/2A,/2 F,F, | A,/2G,/2 E,2- |
w: Come_ fill up your glass-es and let_ us be mer-*ry,
w: Hush,_ hush, in the dis-tance there’s foot-*steps ap-proa-*ching.
%5
E,z E,/2G,/2 | B,B,E | G,G,B, | B,/2A,/2 F,D, | E,3- |
w: _ For to rob bags of plun-der it is_ our in-tent.
w: _ Stand,_ stand and de-li-ver, it is_ our watch cry.
%10
E,z D,/2E,/2 | F,F,F, | E,/2F,/2 G,2- | G,z F,/2G,/2 | A,B, B,/2A,/2 |
w: _ As we roam through the val-*ley,_ Where the li-lies and the
%15
G,/2A,/2 B,2- | B,z G,/2A,/2 | B,B,E | G,E,G, | B,/2A,/2 F,D, | E,3- |
w: ro-*ses,_ And the Beau-ty of Cash-mere lay droo-*ping its head.
%21
E,z D,/2E,/2 |
w: _ Then a-
M:4/4
F,3 E,/2F,/2 | G,3 F,/2G,/2 |
w: way, then a-way, then a-
M:3/4
A,/2G,/2 A,/2B,/2 C/2D/2 | E3- |
w: way______
%26
Ez D/2C/2 | B,B, B,/2E/2 | G,E, G,/2B,/2 | B,/2A,/2 F,D, | E,3- | HE, z 
w: _ To the caves in yon-der moun-tain where the rob-*bers re-treat._
%
% BASS
V:4 name=“Bass” clef=bass
z | z3 | z3 | B,/2C,/2 D,B, | C,/2E,/2 E,2- |
w: let_ us be mer-*ry,
w: foot-*steps ap-proa-*ching.
%5
E,z (E,/2E,/2) | E,D,C, | B,C,B, | G,B,B, | E,3- |
w: _ For to rob bags of plun-der it is our in-tent.
w: _ Stand,_ stand and de-li-ver, it is our watch cry.
%10
E,z D,/2E,/2 | B,B,B, | C,/2D,/2 E,2- | E,z D,/2E,/2 | A,A, C,/2D,/2 |
w: _ As we roam through the val-*ley,_ Where the li-lies and the
%15
B,/2C,/2 E,2- | E,z E,/2E,/2 | E,D,C, | B,C,B, | A,B,B, | E,3- |
w: ro-*ses,_ And the Beau-ty of Cash-mere lay droo-ping its head.
%21
E,zz |
w: _
M:4/4
z B,/2>B,/2 B,z | z E,/2>E,/2 E, D,/2E,/2 |
w: then a-way, then a-way, then a-
M:3/4
F,/2E,/2 F,/2G,/2 A,/2F,/2 | E,3- |
w: way______
%26
E,z B,/2B,/2 | E,D, C,/2C,/2 | B,C, B,/2B,/2 | A,B,B, | E,3- | HE, z 
w: _ To the caves in yon-der moun-tain where the rob-bers re-treat._