Some of these make sense only in the header portion of a tune, while others may be used inside the music portion to change the information.

Some programs (such as abc2ps) now accept notation such as: [K:...] to change information inside a line of music. But this notation might be ignored by some ABC software.

Now for detailed descriptions:

A: area

The A: header line is not seen much. Its intent is to list geographic areas where particular versions of tunes are found. This function overlaps somewhat with the S: line.

B: book

The B: header line is used to give a list of publications where the tune may be found.

C: composer

The composer's name will be shown at the upper-right of the first staff by ABC formatting programs. For tunes known to be traditional, C:Trad is probably a good idea so that people don't think the composer has just been ignored.

D: discography

The D: header line is used to list recordings of the tune.

E: elemskip

F: file name

G: group

H: history

The H: line is used for historical information about the tune. Dates, names of variants, uses in performances are all appropriate here.

I: information

K: key

The K: line is the last line of a tune's header. It may be repeated inside the tune to get a change of key signature. The classical modes are recognized, and may be abbreviated to their first three letters. Minor can be indicated by just "m". Some examples:

K:D	D major	2 sharps
K:Dmaj	D major	2 sharps
K:Dmajor	D major	2 sharps
K:Dm	D minor	1 flat
K:Dmin	D minor	1 flat
K:Dminor	D minor	1 flat
K:C	C major	No sharps or flats
K:Am	A minor	No sharps or flats
K:DDor	D Dorian	No sharps or flats
K:DDorian	D Dorian	No sharps or flats
K:ELyd	E Lydian	No sharps or flats
K:DMix	D Mixolydian	1 sharp
K:DPhr	D Phrygian	2 flats
K:DLyd	D Lydian	3 sharps

There is also a mechanism for giving arbitrary key signatures, for music that uses non-classical scales. As of this writing (early 1999) only a few programs implement it. It is simple: Give explicit notes with accidentals. They may be combined with a key signature. Here are some examples. The first is often seen in Scottish bagpipe music, with an explicit G natural to make it clear that this isn't A major. The rest should be familiar to any Balkan, Klezmer, or Middle-Eastern musician.

K:Amix=g	A mixolydian	two sharps + advisory G natural
K:Dphr^F	D hijaz/freygish	2 flats and 1 sharp
K:Cdor^F	C misheberach	2 flats and 1 sharp
K:_B_e^F	same, no tonic	2 flats and 1 sharp
K:D_e_B^f^c	D zengule	2 flats and 2 sharps
K:GDor^c	G misheberach	Bb plus C#

It is conventional to use upper-case letters for the key, though there have been enough examples of lower-case keys to encourage the software to ignore the case. The mode names may be upper or lower case, and are usually abbreviated. The "maj" and "major" mode indicators are almost never used, and some software might not recognize it. For explicit key signatures, the case is significant to formatting programs, since this says where to put the accidental on the staff.

In addition, there are two keys specifically for notating highland bagpipe tunes: K:HP doesn't put a key signature on the music, as is common with many tune books of this music, while K:Hp marks the stave with F sharp, C sharp and G natural. Both force all the beams and staffs to go downwards. These correspond to the two conventional ways of notating bagpipe music.

L: note length

M: meter

This is the musical meter, expressed as a fraction. There are also several special meters that may be used:

M:C	Common time, the same as M:4/4.
M:C|	Cut time, the same as M:2/2.
M:none	Free meter, no time signature and no checking.

Some ABC software has the ability to add up the lengths of measures and warn you if there is an error. This should always be an option, of course, because so many musical styles include occasional measures with extra beats. M:none should turn off any such error checking. Some ABC software assumed M:4/4 as the default, while other programs may assume M:none.

N: notes

The N: header lines are used to include arbitrary notes about a tune. Many ABC programs have options to either display or suppress these notes. Try not to use N: lines for information that is best done with a more specific header line, because very little software will know how to use information in N: lines.

O: origin

The O: line is used rather inconsistently, to indicate either a place or a person that the music came from. For a person, S: is probably better.

P: parts

Q: tempo

The Q: line gives a tempo, in beats per minute, and is mused by programs such as playabc and abc2midi to determine the speed. Formatting programs will put a tempo indication at the upper-left of the staff. There are several recognized formats for a T: line:

Q:1/4=112	Note and count (preferred)
Q:140	Count only, L: used for note length
Q:C2=80	C is the basic note length from the L: line
Q:Andante	Words are only printed, not used

If no Q: line is used, or only a word is given, play programs such as abc2midi and playabc usually assume a tempo of 100 for the L: note length. You can also expect programs that play ABC will have options to override the tempo, so Q: lines are really just suggestions.

R: rhythm

The R: header line gives a name for the tune's rhythm. This is mostly used for lookup purposes. This use is somewhat limited by due to the spelling variants that people use. Only a few ABC programs use this information. For example, abc2midi will interpret R:hornpipe by playing the small notes unequally.

V: voice

A few ABC programs have implemented multi-voice notation that is not yet part of the official standard, but

S: source

T: title

The T: title line should be the second of a tune's header lines. It may be repeated if there are several titles. ABC formatters will typically show the first such title as the main title, and the others as subtitles in a different font. The T: field can also be used within a tune to name parts of a tune, though you often see P: used for this purpose.

W: words (below the music)

The upper-case W: line is used to supply lyrics that should be separated from the music. Formatting programs like abc2mtex and abc2ps will show these lines below the music. See the Words section for details.

w: words (below the notes)

The lower-case w: line is used to supply lyrics that should be placed below the most recent staff, with the words aligned with notes. See the Words section for details.

X: index number

A tune's index number is used like the track number in a recording, and must be the first line in an ABC tune's header. Some ABC software uses this to select a single tune from a file. It is sometimes omitted in single-tune files, but this is not a good idea, because some programs won't recognize a tune without its X: line.

The value on an X: line should be a (non-negative) integer. Some people have suggested using arbitrary strings as indentifiers, but this will confuse a some software. X:0 seems to work with all ABC software, and it is sometimes used for introductory musical information in a file with multiple tunes - often with no actual music, just headers.

Every tune in a file should have a different X: number, because if two have the same number, you may not be able to use the second. It's probably a good idea to make sure that the numbers are in increasing order. They don't need to be consecutive.

A: transcription notes

The Z: line is used to hold information about who did the ABC transcription, and sometimes includes simply information about the source (though this really belongs in the S: line). Email addresses and URLs are appropriate here, and other contact information such as phone numbers or postal addresses may be included.

Copyright 2001, 2002 by John Chambers