The chopro format is a pseudo-standard format for song lyrics with
chords.
The basic format is simply plain text with chords in brackets.
Some extra markup is added in braces, in the form
{keyword: value} (some keywords does not use a value).
A common example may look like this:
{title: Yesterday}
{subtitle: Beatles}
{define: C/G base-fret 0 frets 3 3 2 0 1 0}
[G]Yesterday[F#m], all my [B7]troubles seemed so [Em]far away
[C]Now it [D]looks as though there [C]here to [G]stay
...
The core of the format is simply text lines, with chord names inserted in brackets.
{title: [Title of the song]} specifies the title of the song.
Can be abbreviated to {t: ...}.
{subtitle: [subtitle]} specifies anything that should be prominently
displayed under the title of the song.
Typically the composer / author / band, possibly with a year or record
name added.
A song can have multiple subtitles (but only one title).
Can be abbreviated to {st: ...}.
{define: [chordname] base-fret [basefret] frets [e] [a] [d] [g] [b] [e]}
Define how chordname should be played.
basefret is the fret where the barre is applied, or 0 if the chord
is not a barre chord.
The keyword frets is followed by the fret to press for each string
(minus basefret if the chord is a barre chord).
0 means the string is played open.
x means that the string is not played.
Each define is valid for the current song only.
(Chord3 has built-in definitions of more than 100 common chord
definitions plus aliases.)
{columns: [n]} specifies how many columns should be used for the
text of this song.
Defaults to 1.
Can be abbreviated to {col: [n]}.
The following tags can be used along with the regular text-and-chord lines:
{comment: [text]} is a line that is printed along with the text in a
different font.
The text might be instructions or any kind of interesting annotations.
{c: ...}, {ci: ...}, and {cb: ...} are aliases for {comment: ...}.
{start_of_chorus} (or {soc}) marks the start of the chorus.
The chorus itself consists of regular text-and-chord lines.
{end_or_chorus} (or {eoc}) marks the end of the chorus.
The start and end markers should be on separate lines.
{start_of_tab} and {end_of_tab} wrabs tabulature, which is currently
simply handled as preformatted (and monospaced) text.
These can be abbreviated as {sot} and {eot}.
{colb} is an explicit end of the current column
(and page, if on the last column).
{page_break} (or {np}) is an explicit page break.
{new_song} ends the current song and starts a new one
(by default, each separate file is a song).