A list of the main changes (excluding typos corrected and minor clarifications) written as the new standard took shape. In many cases this contains links to the relevant discussions on the abcusers mailing list.

Historical note: Dates were added from July 2011 on so that people checking this list can see what has changed since they last visited.

April 2011: Abc 2.0 changed the A: field to contain author (lyrics) information rather than area (region of tune origin) information. Although useful, this modification has not been widely adopted by the abc user community and, more importantly, is not backwards compatible.

Abc 2.1 reverts to the original use for the A: field but this field is now deprecated and, as suggested in abc 2.0, all tune origin information can be encoded in the O: field - see outdated information field syntax.

Possible alternatives for author information (for example, a:) are up for discussion.

July 2011: The line-breaking section (section 2.3 in version 2.0) has been rewritten for clarification. It has also been split into two parts - 2.2.4 Empty lines and line-breaking on the basics of empty lines and line-breaking and 6.1.1 Typesetting line-breaks.

July 2011: English.abc has been rewritten with some inline fields.

9th July 2011: Section 12, now called dialects, strict / loose interpretation and backwards compatibility, has been completely rewritten with the aim of pulling together the main dialects of abc and re-establishing the backwards compatibility that was lost between drafts 1.7.6 and 2.0.

9th July 2011: As part of the work on reducing dialects, the decoration delimiter has been changed from + back to ! - see 4.14 Decorations and 12.1.2 Decoration dialects.

9th July 2011: In Jef Moine's suggestion for line-breaking (see below) he pointed out that this is used solely for typesetting programs and so should be included in a separate section (9b). I also noticed that section 4.6 of version 2.0 was solely for typesetting spaces. However, I didn't feel that the section on clefs (6.0 of version 2.0) merited a top level section all to itself. As a result I have moved clefs to section 4.6 and created a new section 6. Typesetting and playback, which also includes section 6.1.2 Typesetting extra space (previously 4.6).

I also took the opportunity to restructure section 2, abc files, tunes and fragments, somewhat.

Note that the standard may undergo more restructuring at some point in the future so this is not necessarily the finalised version of the section ordering.

9th July 2011: A new section, 2.1 Abc file identification, has been introduced, loosely based on Jef Moine's suggestion at http://xa.yimg.com/kq/groups/16387185/141812565/name/file.xml. The file structure text has been moved into 2.2 Abc file structure.

9th July 2011: A new section 6.1.1, typesetting line-breaks, has been created, based on Jef Moine's suggestion at http://xa.yimg.com/kq/groups/16387185/567662222/name/linebreak.xml and subsequent discussions on the abcusers mail list. This complements the new section, 12.1.1 Line-breaking dialects.

9th July 2011 and subsequently: A number of sections have been marked as VOLATILE, indicating that they are under active discussion on the abcusers mailing list, or as TODO, meaning that changes need to be made.

These indicators are not comprehensive so the lack of a VOLATILE / TODO indication does not necessarily mean the section is finalised.

9th July 2011: 2.2.4 Empty lines and line-breaking has been updated to clarify that a line consisting entirely of white-space is treated as an empty line.

11th July 2011: 4.17 Chords and unisons has been updated with a clarification for chords with different note lengths (see http://tech.groups.yahoo.com/group/abcusers/message/3527 and subsequent discussion).

12th July 2011: 2.2.5 Comments and remarks and 2.2.6 Continuation of input lines have swapped places and have been updated to clarify the interaction of comments and continuations.

12th July 2011: 3.0 Information fields (and related sections) have been updated following a decision about X: and T: syntax - see also outdated tune header syntax.

12th July 2011: 10. Outdated syntax has been updated with a number of changes, plus some tentative definitions of terms.

19th July 2011: 3.1.7 Unit note length updated to clarify that all powers of two from L:1 to L:1/512 are available, although L:1/64 and shorter values are optional (L:1/512 may seem excessive, but it is available in Sibelius http://www.sibelius.com/products/sibelius/acorninfo.html so might as well be in abc software wishing to provide it).

20th July 2011: The table in 3.0 Information fields has been updated with links to relevant sections, columns reordered and an additional column indicating fields that can be inlined (mostly as per Jef Moine's suggestion at http://xa.yimg.com/kq/groups/16387185/1265172711/name/info.xml).

20th July 2011: Two new sections added - 3.1.15 R: - rhythm and 3.1.16 Background information for completeness.

26th July 2011: New section added - 2.3 Embedded abc and abc fragments following discussions in message 4181 and subsequent debate.

28th July 2011: 2.2.3 Free text and typeset text clarified (along with 11.4.5 Text directives which has now been split into two sections, the second one being 11.4.7 Separation directives). Note that none of the rules have changed since abc 2.0 - this just clarifies the usage and points towards future changes.

28th July 2011: A new section (3.1.17) has been added, about the I: - instruction field and how it relates to %% directives.

8th August 2011: A new %%writefields directive has been introduced in 11.4.6 Information directives, allowing the user to choose which information fields are written in the printed score. This is an alternative to some miscellaneous directives listed in 2.0.

Alongside this new directive, the typesetting details for various information fields, previously scattered about section 3.1., have been combined to form a new section 6.1.3 Typesetting information fields.

8th August 2011: A new section (11.6.) has been added, with links to further information about directives.

11th August 2011: The backslash has been restored to its original (pre 2.0) definition (i.e. for suppressing line-breaks). This is discussed in continuation of input lines and a new section suppressing score line-breaks - see messages 4566 , 4581 and 4607 and subsequent discussions.

12th August 2011: The former section 3.3 Extended information fields has been revised and included as part of section 3.1.17 I: - instruction.

12th August 2011: A new section 3.3 Field continuation has been added - see messages 4691 and 4765 and subsequent discussions.

13th August 2011: New sections 1.1 How to read this document and 1.2 How to avoid reading this document have been added. More importantly all commonly used terminology (e.g. abc file, abc tune, etc) is now linked back to the section in which it is defined - section 1.1 provides index of these definitions.

13th August 2011: The %%abc-copyright and %%abc-edited-by extended information fields have been deprecated in favour of the Z: - transcription field - see outdated directives.

13th August 2011: The old Q:tempo usage has been deprecated - see outdated information field syntax.

13th August 2011: A recommendation has been added regarding the order of information fields in the tune header.

14th August 2011: The somewhat cryptic append/replace table in section 3.0 of abc 2.0 has been replaced with instructions about repeated information fields

14th August 2011: The list of midi instruments (section 14.1 in abc 2.0) has been removed and replaced with a link to http://www.midi.org/techspecs/gm1sound.php.

14th August 2011: Multi-measure invisible rests have been defined.

29th November 2011: The section on text strings (8.2), together with the appendix containing tables on supported accents & ligatures (14.1), have been revised - see message 4874 and subsequent discussions.

29th November 2011: The voice overlay section (7.4) has been updated and a new section, disallowed voice overlay (10.6.1), introduced.

30th November 2011: The rules for aligned lyrics (the w: field) have been extended and section 5 split into subsections - see messages 4642, 4944 and subsequent discussions.

16th December 2011 - 20th December 2011: A large number of minor changes (based on feedback in the abcusers mail) have been inserted, including, but not limited to:

• a recommendation to use ";" as a separator for the O: field (see 3.1.4)
• the P: parts field has been marked as VOLATILE pending a clarification over the way it interacts with the V: field in multi-voice music (see 3.1.9)
• complaint software should be able to handle 128th notes (see 4.3)
• the octave=<number> modifier has been introduced for K: and V: fields (see 4.6)
• examples updated in 4.10 - || replaced by :|
• decorations are allowed in chords (see 4.17)
• a clarification and discussion has been added about the lack of backwards compatibility (under certain circumstances) in the extension of the w: field alignment rules (see 5.1 and 10.6)
• a disclaimer for the stylesheet directives (see 11.0.1)