Doc -- Add Extending to @seealso list.

[lilypond.git] / Documentation / contributor / doc-work.itexi

@c -*- coding: utf-8; mode: texinfo; -*-
@node Documentation work
@chapter Documentation work

There are currently 11 manuals for LilyPond, not including the
translations.  Each book is available in HTML, PDF, and info.  The
documentation is written in a language called @code{texinfo} --
this allows us to generate different output formats from a single
set of source files.

To organize multiple authors working on the documentation, we use a
Version Control System (VCS) called git, previously discussed in
@ref{Starting with git}.

@menu
* Introduction to documentation work::
* Documentation suggestions::
* Texinfo introduction and usage policy::
* Documentation policy::
* Tips for writing docs::
* Updating docs with convert-ly::
* Docstrings in scheme::
* Translating the documentation::
@end menu


@node Introduction to documentation work
@section Introduction to documentation work

Our documentation tries to adhere to our @ref{Documentation
policy}.  This policy contains a few items which may seem odd.
One policy in particular is often questioned by potential
contributors: we do not repeat material in the Notation Reference,
and instead provide links to the @qq{definitive} presentation of
that information.  Some people point out, with good reason, that
this makes the documentation harder to read.  If we repeated
certain information in relevant places, readers would be less
likely to miss that information.

That reasoning is sound, but we have two counter-arguments.
First, the Notation Reference -- one of @emph{five} manuals for
users to read -- is already over 500 pages long.  If we repeated
material, we could easily exceed 1000 pages!  Second, and much
more importantly, LilyPond is an evolving project.  New features
are added, bugs are fixed, and bugs are discovered and documented.
If features are discussed in multiple places, the documentation
team must find every instance.  Since the manual is so large, it
is impossible for one person to have the location of every piece
of information memorized, so any attempt to update the
documentation will invariably omit a few places.  This second
concern is not at all theoretical; the documentation used to be
plagued with inconsistent information.

If the documentation were targeted for a specific version -- say,
LilyPond 2.10.5 -- and we had unlimited resources to spend on
documentation, then we could avoid this second problem.  But since
LilyPond evolves (and that is a very good thing!), and since we
have quite limited resources, this policy remains in place.

A few other policies (such as not permitting the use of tweaks in
the main portion of NR 1+2) may also seem counter-intuitive, but
they also stem from attempting to find the most effective use of
limited documentation help.


@node Documentation suggestions
@section Documentation suggestions

@subheading Small additions

For additions to the documentation,

@enumerate

@item
Tell us where the addition should be placed. Please include both
the section number and title (i.e. "LM 2.13 Printing lyrics").

@item
Please write exact changes to the text.

@item
A formal patch to the source code is @emph{not} required; we can
take care of the technical details. Here is an example of a
perfect documentation report:

@verbatim
To: lilypond-devel@gnu.org
From: helpful-user@example.net
Subject: doc addition

In LM 2.13 (printing lyrics), above the last line ("More options,
like..."), please add:

----
To add lyrics to a divided part, use blah blah blah.  For example,

\score {
  \notes {blah <<blah>> }
  \lyrics {blah <<blah>> }
  blah blah blah
}
----

In addition, the second sentence of the first paragraph is
confusing.  Please delete that sentence (it begins "Users
often...") and replace it with this:
----
To align lyrics with something, do this thing.
----

Have a nice day,
Helpful User
@end verbatim

@end enumerate


@subheading Larger contributions

To replace large sections of the documentation, the guidelines are
stricter. We cannot remove parts of the current documentation
unless we are certain that the new version is an improvement.

@enumerate

@item
Ask on the lilypond-devel maillist if such a rewrite is necessary;
somebody else might already be working on this issue!

@item
Split your work into small sections; this makes it much easier to
compare the new and old documentation.

@item
Please prepare a formal git patch.

@end enumerate

Once you have followed these guidelines, please send a message to
lilypond-devel with your documentation submissions. Unfortunately
there is a strict “no top-posting” check on the mailist; to avoid
this, add:

> I'm not top posting.

(you must include the > ) to the top of your documentation
addition.

We may edit your suggestion for spelling, grammar, or style, and
we may not place the material exactly where you suggested, but if
you give us some material to work with, we can improve the manual
much faster.  Thanks for your interest!


@node Texinfo introduction and usage policy
@section Texinfo introduction and usage policy

@menu
* Texinfo introduction::
* Documentation files::
* Sectioning commands::
* LilyPond formatting::
* Text formatting::
* Syntax survey::
* Other text concerns::
@end menu


@node Texinfo introduction
@subsection Texinfo introduction

The language is called Texinfo; you can see its manual here:

@uref{http://www.gnu.org/software/texinfo/manual/texinfo/}

However, you don't need to read those docs.  The most important
thing to notice is that text is text.  If you see a mistake in the
text, you can fix it.  If you want to change the order of
something, you can cut-and-paste that stuff into a new location.

@warning{Rule of thumb: follow the examples in the existing docs.
You can learn most of what you need to know from this; if you want
to do anything fancy, discuss it on @code{lilypond-devel} first.}


@node Documentation files
@subsection Documentation files

All manuals live in @file{Documentation/}.

In particular, there are four user manuals, their respective master
source files are @file{learning.tely} (LM, Learning Manual),
@file{notation.tely} (NR, Notation Reference),
@file{music-glossary.tely} (MG, Music Glossary), and
@file{lilypond-program} (AU).  Each chapter is written in a separate
file, ending in @file{.itely} for files containing lilypond code, and
@file{.itexi} for files without lilypond code, located in a subdirectory
associated to the manual (@file{learning/} for @file{learning.tely}, and
so on); list the subdirectory of each manual to determine the filename
of the specific chapter you wish to modify.

Developer manuals live in @file{Documentation/} too.  Currently there is
only one: the Contributor's Guide @file{contrib-guide.texi} you are
reading.

Snippet files are part of documentation, and the Snippet List (SL) lives
in @file{Documentation/} just like the manuals.  For information about
how to modify the snippet files and SL, see @ref{LSR work}.


@node Sectioning commands
@subsection Sectioning commands

Most of the manual operates at the

@example
@@node Foo
@@subsubsection Foo
@end example

@noindent
level.  Sections are created with

@example
@@node Foo
@@subsection Foo
@end example

@itemize
@item
Please leave two blank lines above a @@node; this makes it
easier to find sections in texinfo.

@item
Sectioning commands (@@node and @@section) must not appear
inside an @@ignore.  Separate those commands with a space, ie @@n
ode.

@end itemize

Nodes must be included inside a

@example
@@menu
* foo::
* bar::
@@end menu
@end example

@noindent
construct.  These are easily constructed with the emacs
@code{M-x texinfo-all-menus-update} construct, or by this
command-line script:

@example
#!/bin/sh
emacs $1 -batch -f texinfo-all-menus-update -f save-buffer
@end example

@noindent
(save the above as something like @command{texinfo-menus.sh}, make
it executable, then run @command{texinfo-menus.sh foo.itely})


@node LilyPond formatting
@subsection LilyPond formatting

@itemize

@item
Use two spaces for indentation in lilypond examples.  (no
tabs)

@item
All text strings should be prefaced with #.  LilyPond does
not strictly require this, but it is helpful to get users
accustomed to this scheme construct.  ie @code{\set
Staff.instrumentName = #"cello"}

@item
All engravers should have double-quotes around them:

@example
\consists "Spans_arpeggio_engraver"
@end example

Again, LilyPond does not strictly require this, but it is a useful
standard to follow.

@item
Examples should end with a complete bar if possible.

@item
If possible, only write one bar per line.  The notes on each
line should be an independent line -- tweaks should occur on their
own line if possible.  Bad:

@example
\override textscript #'padding = #3 c1^"hi"
@end example

Good:

@example
\override textscript #'padding = #3
c1^"hi"
@end example

@item
Most LilyPond input should be produced with:

@example
@@lilypond[verbatim,quote,relative=2]
@end example

@noindent
or

@example
@@lilypond[verbatim,quote,relative=1]
@end example

If you want to use \layout@{@} or define variables, use

@example
@@lilypond[verbatim,quote]
@end example

In rare cases, other options may be used (or omitted), but ask first.

@item
Inspirational headwords are produced with

@example
@@lilypondfile[quote,ragged-right,line-width=16\cm,staffsize=16]
@{pitches-headword.ly@}
@end example

@item
LSR snippets are linked with

@example
@@lilypondfile[verbatim,lilyquote,ragged-right,texidoc,doctitle]
@{filename.ly@}
@end example

@noindent
excepted in Templates, where `doctitle' may be omitted.

@item
Avoid long stretches of input code.  Noone is going to read
them in print.  Please create a smaller example.  (the smaller
example does not need to be minimal, however)

@item
Specify durations for at least the first note of every bar.

@item
If possible, end with a complete bar.

@item
Comments should go on their own line, and be placed before
the line(s) to which they refer.

@item
Add extra spaces around @{ @} marks; ie

@example
not:          \chordmode @{c e g@}
but instead:  \chordmode @{ c e g @}
@end example

@item
If you only have one bar per line, omit bar checks.  If you
put more than one bar per line (not recommended), then include bar
checks.

@item
If you want to work on an example outside of the manual (for
easier/faster processing), use this header:

@example
\paper @{
  indent = 0\mm
  line-width = 160\mm - 2.0 * 0.4\in
  ragged-right = ##t
  force-assignment = #""
  line-width = #(- line-width (* mm  3.000000))
@}

\layout @{
@}
@end example

You may not change any of these values.  If you are making an
example demonstrating special \paper@{@} values, contact the
Documentation Editor.

@end itemize


@node Text formatting
@subsection Text formatting

@itemize

@item
Lines should be less than 72 characters long.  (I personally
recommend writing with 66-char lines, but don't bother modifying
existing material.)

@item
Do not use tabs.

@item
Do not use spaces at the beginning of a line (except in
@@example or @@verbatim environments), and do not use more than a
single space between words.  `makeinfo' copies the input lines
verbatim without removing those spaces.

@item
Use two spaces after a period.

@item
In examples of syntax, use @@var@{musicexpr@} for a music
expression.

@item
Don't use @@rinternals@{@} in the main text.  If you're
tempted to do so, you're probably getting too close to "talking
through the code".  If you really want to refer to a context, use
@@code@{@} in the main text and @@rinternals@{@} in the @@seealso.

@item
Variables or numbers which consist of a single character
(probably followed by a punctuation mark) should be tied properly,
either to the previous or the next word.  Example:

@example
The variable@@tie@{@}@@var@{a@} ...
@end example

@item
To get consistent indentation in the DVI output it is better
to avoid the @@verbatim environment.  Use the @@example
environment instead if possible, but without extraneous
indentation.  For example, this

@example
@@example
  foo @{
    bar
  @}
@@end example
@end example

@noindent
should be replaced with

@example
@@example
foo @{
  bar
@}
@@end example
@end example

@noindent
where `@@example' starts the line (without leading spaces).

@item
Do not compress the input vertically; this is, do not use

@example
    Beginning of logical unit
    @@example
    ...
    @@end example
    continuation of logical unit
@end example

@noindent
but instead do

@example
Beginning of logical unit

@@example
...
@@end example

@@noindent
continuation of logical unit
@end example

This makes it easier to avoid forgetting the `@@noindent'.  Only
use @@noindent if the material is discussing the same material;
new material should simply begin without anything special on the
line above it.

@item
in @@itemize use @@item
on a separate line like this:

@example
@@itemize
@@item
Foo

@@item
Bar
@end example

Do not use @@itemize @@bullet.

@item
To get LilyPond version, use @@version@{@} (this does not work
inside LilyPond snippets).  If you write "@@version@{@}" (enclosed
with quotes), or generally if @@version@{@} is not followed by a
space, there will be an ugly line break in PDF output unless you
enclose it with

@example
@@w@{ ... @}

  e.g.

@@w@{"@@version@{@}"@}
@end example

@end itemize


@node Syntax survey
@subsection Syntax survey

@itemize
@item
@@c - single line comments
  "@@c NOTE:" is a comment which should remain in the final
  version.  (gp only command ;)
@item
@@ignore ... @@end ignore - multi-line comment

@item
@@cindex - General index. Please add as many as you can.  Don't
  capitalize the first word.
@item
@@funindex - is for a \lilycommand.

@item
@@example ... @@end example - example text that should be set as a
  blockquote.  Any @{@} must be escaped with @@@{ @}@@

@item
@@itemize @@item
A @@item
B ... @@end itemize - for bulleted lists.
  Do not compress vertically like this.

@item
@@code@{@} - typeset in a tt-font. Use for actual lilypond code or
  property/context names.  If the name contains a space, wrap
  the entire thing inside @@w@{@@code@{  @}@}.

@item
@@notation@{@} - refers to pieces of notation, e.g.
  "@@notation@{cres.@}".  Also use to specific lyrics ("the
  @@notation@{A - men@} is centered").  Only use once per subsection
  per term.

@item
@@q@{@} - Single quotes. Used for `vague' terms.

@item
@@qq@{@} - Double quotes.  Used for actual quotes ("he said") or for
  introducing special input modes.

@item
@@tie@{@} - Variables or numbers which consist of a single character
  (probably followed by a punctuation mark) should be tied
  properly, either to the previous or the next word.  Example:
    "The letter@@tie@{@}@@q@{I@} is skipped"

@item
@@var - Use for variables.

@item
@@warning@{@} - produces a "Note: " box. Use for important messages.

@item
@@bs - Generates a backslash inside @@warning.
    Any `\' used inside @@warning (and @@q or @@qq) must be written as `@@bs@{@}'
    (texinfo would also allow \\, but this breaks with PDF output).

@item
@@ref@{@} - link within current manual (type the exact node name inside the
@{@}).

@item
@@ruser@{@} - link to Notation Reference.

@item
@@rlearning@{@} - link to Learning Manual.

@item
@@rglos@{@} - link to the Music Glossary.

@item
@@rprogram@{@} - link to Application Usage.

@item
@@rlsr@{@} - link to a Snippet section.

@item
@@rinternals@{@} - link to the Internals Reference.

@item
@@rextend@{@} - link to Extending LilyPond.

@item
@@uref@{@} - link to an external url.

@end itemize



@node Other text concerns
@subsection Other text concerns

@itemize

@item
References must occur at the end of a sentence, for more
information see @@ref@{the texinfo manual@}.  Ideally this should
also be the final sentence of a paragraph, but this is not
required.  Any link in a doc section must be duplicated in the
@@seealso section at the bottom.

@item
Introducing examples must be done with

@example
. (ie finish the previous sentence/paragaph)
: (ie `in this example:')
, (ie `may add foo with the blah construct,')
@end example

The old @qq{sentence runs directly into the example} method is not
allowed any more.

@item
Abbrevs in caps, e.g., HTML, DVI, MIDI, etc.

@item
Colon usage

@enumerate

@item
To introduce lists

@item
When beginning a quote: "So, he said,...".

This usage is rarer.  Americans often just use a comma.

@item
When adding a defining example at the end of a sentence.

@end enumerate

@item
Non-ASCII characters which are in utf-8 should be directly used;
this is, don't say `Ba@@ss@{@}tuba' but `Baßtuba'.  This ensures
that all such characters appear in all output formats.

@end itemize




@node Documentation policy
@section Documentation policy

@menu
* Books::
* Section organization::
* Checking cross-references::
* General writing::
* Technical writing style::
@end menu

@node Books
@subsection Books

There are four parts to the documentation: the Learning Manual,
the Notation Reference, the Program Reference, and the Music
Glossary.

@itemize

@item
Learning Manual:

The LM is written in a tutorial style which introduces the most
important concepts, structure and syntax of the elements of a
LilyPond score in a carefully graded sequence of steps.
Explanations of all musical concepts used in the Manual can be
found in the Music Glossary, and readers are assumed to have no
prior knowledge of LilyPond.  The objective is to take readers to
a level where the Notation Reference can be understood and
employed to both adapt the templates in the Appendix to their
needs and to begin to construct their own scores.  Commonly used
tweaks are introduced and explained.  Examples are provided
throughout which, while being focussed on the topic being
introduced, are long enough to seem real in order to retain the
readers' interest.  Each example builds on the previous material,
and comments are used liberally.  Every new aspect is thoroughly
explained before it is used.

Users are encouraged to read the complete Learning Manual from
start-to-finish.


@item
Notation Reference: a (hopefully complete) description of LilyPond
input notation.  Some material from here may be duplicated in the
Learning Manual (for teaching), but consider the NR to be the
"definitive" description of each notation element, with the LM
being an "extra".  The goal is _not_ to provide a step-by-step
learning environment -- do not avoid using notation that has not
be introduced previously in the NR  (for example, use \break if
appropriate).  This section is written in formal technical writing
style.

Avoid duplication.  Although users are not expected to read this
manual from start to finish, they should be familiar with the
material in the Learning Manual (particularly ``Fundamental
Concepts''), so do not repeat that material in each section of
this book.  Also watch out for common constructs, like ^ - _ for
directions -- those are explained in NR 3.  In NR 1, you can
write: DYNAMICS may be manually placed above or below the staff,
see @@ref@{Controlling direction and placement@}.

Most tweaks should be added to LSR and not placed directly in the
.itely file.  In some cases, tweaks may be placed in the main
text, but ask about this first.

Finally, you should assume that users know what the notation
means; explaining musical concepts happens in the Music Glossary.


@item
Application Usage: information about using the program lilypond
with other programs (lilypond-book, operating systems, GUIs,
convert-ly, etc).  This section is written in formal technical
writing style.

Users are not expected to read this manual from start to finish.


@item
Music Glossary: information about the music notation itself.
Explanations and translations about notation terms go here.

Users are not expected to read this manual from start to finish.

@item
Internals Reference: not really a documentation book, since it is
automagically generated from the source, but this is its name.

@end itemize


@node Section organization
@subsection Section organization

@itemize

@item
The order of headings inside documentation sections should
be:

@example
main docs
@@predefined
@@endpredefined
@@snippets
@@seealso
@@knownissues
@end example

@item
You @emph{must} include a @@seealso.

@itemize
@item
The order of items inside the @@seealso section is

@example
Music Glossary:
@@rglos@{foo@},
@@rglos@{bar@}.

Learning Manual:
@@rlearning@{baz@},
@@rlearning@{foozle@}.

Notation Reference:
@@ruser@{faazle@},
@@ruser@{boo@}.

Application Usage:
@@rprogram@{blah@}.

Extending LilyPond:
@@rextend@{frob@}.

Installed Files:
@@file@{path/to/dir/blahz@}.

Snippets: @@rlsr@{section@}.

Internals Reference:
@@rinternals@{fazzle@},
@@rinternals@{booar@}.
@end example

@item
If there are multiple entries, separate them by commas but do not
include an `and'.

@item
Always end with a period.

@item
Place each link on a new line as above; this makes it much easier
to add or remove links.  In the output, they appear on a single
line.

("Snippets" is REQUIRED; the others are optional)

@item
Any new concepts or links which require an explanation should go
as a full sentence(s) in the main text.

@item
Don't insert an empty line between @@seealso and the first entry!
Otherwise there is excessive vertical space in the PDF output.

@end itemize

@item
To create links, use @@ref@{@} if the link is within the same
manual.

@item
@@predefined ... @@endpredefined is for commands in ly/*-init.ly
FIXME?

@item
Do not include any real info in second-level sections (ie 1.1
Pitches).  A first-level section may have introductory material,
but other than that all material goes into third-level sections
(ie 1.1.1 Writing Pitches).

@end itemize


@node Checking cross-references
@subsection Checking cross-references

Cross-references between different manuals are heavily used in the
documentation, but they are not checked during compilation.
However, if you compile the documentation, a script called
check_texi_refs can help you with checking and fixing these
cross-references; for information on usage, cd into a source tree
where documentation has been built, cd into Documentation and look
for check-xrefs and fix-xrefs targets in 'make help' output.  Note
that you have to find yourself the source files to fix
cross-references in the generated documentation such as the
Internals Reference; e.g. you can grep scm/ and lily/.


@node General writing
@subsection General writing

@itemize

@item
Do not forget to create @@cindex entries for new sections of text.
Enter commands with @@funindex, i.e.

@example
@@cindex pitches, writing in different octaves
@@funindex \relative
@end example

@noindent
do not bother with the @@code@{@} (they are added automatically).
These items are added to both the command index and the unified
index.

Both index commands should go in front of the actual material.

@@cindex entries should not be capitalized, ie

@example
@@cindex time signature
@end example

@noindent
is preferred instead of @qq{Time signature},   Only use capital
letters for musical terms which demand them, like D.S. al Fine.

For scheme functions, only include the final part, i.e.,

@example
@@funindex modern-voice-cautionary
     and NOT
@@funindex #(set-accidental-style modern-voice-cautionary)
@end example

@item
Preferred terms:

@itemize

@item
In general, use the American spellings.  The internal lilypond
property names use this spelling.

@item
List of specific terms:

@example
canceled
simultaneous    NOT concurrent
measure: the unit of music
bar line: the symbol delimiting a measure   NOT barline
note head   NOT notehead
chord construct   NOT chord (when referring to <>)
@end example

@end itemize

@end itemize


@node Technical writing style
@subsection Technical writing style

These refer to the NR.  The LM uses a more gentle, colloquial
style.

@itemize

@item
Do not refer to LilyPond in the text.  The reader knows what the
manual is about.  If you do, capitalization is LilyPond.

@item
If you explicitly refer to @q{lilypond} the program (or any other
command to be executed), write @code{@@command@{lilypond@}}.

@item
Do not explicitly refer to the reader/user.  There is no one else
besides the reader and the writer.

@item
Avoid contractions (don't, won't, etc.).  Spell the words out completely.

@item
Avoid abbreviations, except for commonly used abbreviations of foreign
language terms such as etc. and i.e.

@item
Avoid fluff (@qq{Notice that,} @qq{as you can see,}
@qq{Currently,}).

@item
The use of the word @q{illegal} is inappropriate in most cases.
Say @q{invalid} instead.

@end itemize


@node Tips for writing docs
@section Tips for writing docs

In the NR, I highly recommend focusing on one subsection at a
time.  For each subsection,

@itemize

@item
check the mundane formatting.  Are the headings (@@predefined,
@@seealso, etc.) in the right order?

@item
add any appropriate index entries.

@item
check the links in the @@seealso section -- links to music
glossary, internal references, and other NR sections are the main
concern.  Check for potential additions.

@item
move LSR-worthy material into LSR.  Add the snippet, delete the
material from the .itely file, and add a @@lilypondfile command.

@item
check the examples and descriptions.  Do they still work?
@strong{Do not} assume that the existing text is
accurate/complete; some of the manual is highly out of date.

@item
is the material in the @@knownissues  still accurate?

@item
can the examples be improved (made more explanatory), or is there
any missing info?  (feel free to ask specific questions on -user;
a couple of people claimed to be interesting in being
@qq{consultants} who would help with such questions)

@end itemize

In general, I favor short text explanations with good examples --
@qq{an example is worth a thousand words}.  When I worked on the
docs, I spent about half my time just working on those tiny
lilypond examples.  Making easily-understandable examples is much
harder than it looks.


@subsubheading Tweaks

In general, any \set or \override commands should go in the
@qq{select snippets} section, which means that they should go in
LSR and not the .itely file.  For some cases, the command
obviously belongs in the @qq{main text} (i.e. not inside
@@predefined or @@seealso or whatever) -- instrument names are a
good example of this.

@example
\set Staff.instrumentName = #"foo"
@end example

On the other side of this,

@example
\override Score.Hairpin #'after-line-breaking = ##t
@end example

clearly belongs in LSR.

I'm quite willing to discuss specific cases if you think that a
tweaks needs to be in the main text.  But items that can go into
LSR are easier to maintain, so I'd like to move as much as
possible into there.


It would be @qq{nice} if you spent a lot of time crafting nice
tweaks for users@dots{} but my recommendation is @strong{not} to do
this.  There's a lot of doc work to do without adding examples of
tweaks.  Tweak examples can easily be added by normal users by adding
them to the LSR.

One place where a documentation writer can profitably spend time writing
or upgrading tweaks is creating tweaks to deal with known issues.  It
would be ideal if every significant known issue had a workaround to avoid
the difficulty.

@seealso
@ref{Adding and editing snippets}.


@node Updating docs with convert-ly
@section Updating doc with @command{convert-ly}

cd into @file{Documentation/} and run

@example
find . -name '*.itely' | xargs convert-ly -e
@end example

@noindent
This also updates translated documentation.



@node Docstrings in scheme
@section Docstrings in scheme

Material in the Internals reference is generated automatically
from our source code.  Any doc work on Internals therefore
requires modifying files in @file{scm/*.scm}.  Texinfo is allowed
in these docstrings.

Most documentation writers never touch these, though.  If you want
to work on them, please ask for help.


@node Translating the documentation
@section Translating the documentation

The mailing list @code{translations@@lilynet.net} is dedicated to
LilyPond web site and documentation translation; on this list, you will
get support from the Translations Meister and experimented translators,
and we regularly discuss translations issues common to all languagues.
All people interested in LilyPond translations are invited to subscribe
to this list regardless of the amount of their contribution, by sending
an email to @code{translations-request@@lilynet.net} with subject
@code{subscribe} and an empty message body.

@menu
* Getting started with documentation translation::
* Documentation translation details::
* Documentation translation maintenance::
* Translations management policies::
* Technical background::
@end menu

@node Getting started with documentation translation
@subsection Getting started with documentation translation

First, get the sources from the Git repository, see @ref{Documentation
translations source code}.

@menu
* Translation requirements::
* Which documentation can be translated::
* Starting translation in a new language::
@end menu

@node Translation requirements
@unnumberedsubsubsec Translation requirements

Working on LilyPond documentation translations requires the following
pieces of software, in order to make use of dedicated helper tools:

@itemize
@item Python 2.4 or higher,
@item GNU Make,
@item Gettext,
@item Git.
@end itemize

It is not required to build LilyPond and the documentation to
translate the documentation.  However, if you have enough time and
motivation and a suitable system, it can be very useful to build at
least the documentation so that you can check the output yourself and
more quickly; if you are interested, see @ref{Compiling from source}.


@node Which documentation can be translated
@unnumberedsubsubsec Which documentation can be translated

FIXME: take into account the new web site integration in main sources.

The makefiles and scripts infrastructure currently supports translation
of the following documentation:

@itemize
@item documentation index (HTML);
@item the Learning Manual, the Notation Reference and Application Usage
-- Texinfo source, PDF and HTML output; Info output might be added if
there is enough demand for it;
@item the Changes document.
@end itemize

Support for translating the following pieces of documentation should be
added soon, by decreasing order of priority:

@itemize
@item automatically generated documentation: markup commands,
predefined music functions;
@item the Snippets List;
@item the Internals Reference.
@end itemize


@node Starting translation in a new language
@unnumberedsubsubsec Starting translation in a new language

At top of the source directory, do

@example
./autogen.sh
@end example

@noindent
or (if you want to install your self-compiled LilyPond locally)

@example
./autogen.sh --prefix=$HOME
@end example

@noindent
If you want to compile LilyPond -- which is almost required to build
the documentation, but is not required to do translation only -- fix
all dependencies and rerun @command{./configure} (with the same
options as for @command{autogen.sh}).

Then @command{cd} into @file{Documentation/} and run

@example
make ISOLANG=@var{MY-LANGUAGE} new-lang
@end example

@noindent
where @var{MY-LANGUAGE} is the ISO 639 language code.

Finally, add a language definition for your language in
@file{python/langdefs.py}.

Before starting the real translation work, it is recommended to commit
changes you made so far to Git, so e.g. you are able to get back to
this state of the sources easily if needed; see @ref{Sharing your
changes}.


@node Documentation translation details
@subsection Documentation translation details

Please follow all the instructions with care to ensure quality work.

All files should be encoded in UTF-8.

@menu
* Files to be translated::
* Translating the Learning Manual and other Texinfo documentation::
* Translating the Notation Reference and Application Usage::
* Translating the Documentation index index.html.in::
@end menu

@node Files to be translated
@unnumberedsubsubsec Files to be translated

@include contributor/doc-translation-list.itexi

@node Translating the Learning Manual and other Texinfo documentation
@unnumberedsubsubsec Translating the Learning Manual and other Texinfo documentation

@iftex
@vskip 12pt
@end iftex
@cartouche
@b{Note:} node names and section titles are now translated directly in
Texinfo source files. In case you have files in your working tree that
have not been converted, please pull first, then run

@example
make -C Documentation/po doc
export LYDOC_LOCALEDIR=Documentation/po/out-www
export PYTHONPATH=python:python/auxiliar
scripts/auxiliar/tely-gettext.py @var{manual.tely}
@end example

@noindent
This will also update files included in @file{@var{manual}.tely}, and of
course this script can be used for individual @file{@var{foo}.itely}
files too.
@end cartouche

Every piece of text should be translated in the source file, except
Texinfo comments, text in @code{@@lilypond} blocks and a few cases
mentioned below.

Node names are translated, but the original node name in English should
be kept as the argument of @code{@@translationof} put after the section
title; that is, every piece in the original file like

@example
@@node Foo bar
@@@var{section_command} Bar baz
@end example

@noindent
should be translated as

@example
@@node @var{translation of Foo bar}
@@@var{section_command} @var{translation of Bar baz}
@@translationof Foo bar
@end example

The argument of @code{@@rglos} commands and the first argument of
@code{@@rglosnamed} commands must not be translated, as it is the node
name of an entry in Music Glossary.

Every time you translate a node name in a cross-reference, i.e. the
argument of commands @code{@@ref, @@rprogram, @@rlearning, @@rlsr,
@@ruser} or the first argument of their @code{@var{*}named} variants,
you should make sure the target node is defined in the correct source
file; if you do not intend to translate the target node right now, you
should at least write the node definition (that is, the @code{@@node
@@@var{section_commmand} @@translationof} trio mentioned above) in the
expected source file and define all its parent nodes; for each node you
have defined this way but have not translated, insert a line that
contains @code{@@untranslated} and append @code{ @@c external} to the
line that contains @code{@@translationof}. That is, you should end up
for each untranslated node with something like

@example
@@node @var{translation of Foo bar}
@@@var{section_command} @var{translation of Bar baz}
@@translationof Foo bar @@c external

@@untranslated
@end example

@noindent
Finally, press in Emacs @key{C-c C-u C-a} to update or generate
menus. This process should be made easier in the future, when the helper
script @command{texi-langutils.py} and the makefile target are updated.

Some pieces of text manipulated by build scripts that appear in the
output are translated in a @file{.po} file -- just like LilyPond output
messages -- in @file{Documentation/po}.  The Gettext domain is named
@code{lilypond-doc}, and unlike @code{lilypond} domain it is not managed
through the Free Translation Project.


Take care of using typographic rules for your language, especially in
@file{macros.itexi}.


Please keep verbatim copies of music snippets (in @code{@@lilypond}
blocs).  However, some music snippets containing text that shows in
the rendered music, and sometimes translating this text really helps
the user to understand the documentation; in this case, and only in
this case, you may as an exception translate text in the music
snippet, and then you must add a line immediately before the
@code{@@lilypond} block, starting with

@example
@@c KEEP LY
@end example

@noindent
Otherwise the music snippet would be reset to the same content as the
English version at next @command{make snippet-update} run -- see
@ref{Updating documentation translation}.

When you encounter

@example
@@lilypondfile[<number of fragment options>,texidoc]@{@var{filename.ly}@}
@end example

@noindent
in the source, open @file{Documentation/snippets/@var{filename}.ly},
translate the @code{texidoc} header field it contains, enclose it with
@code{texidoc@var{MY-LANGUAGE} = "} and @code{"}, and write it into
@file{Documentation/@var{MY-LANGUAGE}/texidocs/@var{filename}.texidoc}.
Additionnally, you may translate the snippet's title in @code{doctitle}
header field, in case @code{doctitle} is a fragment option used in
@code{@@lilypondfile}; you can do this exactly the same way as
@code{texidoc}.  For instance,
@file{Documentation/@var{MY-LANGUAGE}/texidocs/@var{filename}.texidoc}
may contain

@example
doctitlees = "Spanish title baz"
texidoces = "
Spanish translation blah
"
@end example

@noindent
Then, you should get these translated strings into compiled snippets in
@file{Documentation/snippets}, see @q{General guidelines} in @ref{Adding
and editing snippets}.

@code{@@example} blocs need not be verbatim copies, e.g. variable
names, file names and comments should be translated.

Finally, please carefully apply every rule exposed in @ref{Texinfo
introduction and usage policy}, and @ref{Documentation policy}.  If one
of these rules conflicts with a rule specific to your language, please
ask the Translation meister on @email{translations@@lilynet.net} list
and/or the Documentation Editors on @email{lilypond-devel@@gnu.org}
list.


@node Translating the Notation Reference and Application Usage
@unnumberedsubsubsec Translating the Notation Reference and Application Usage

Copy @file{notation.tely} (or @file{application.tely},
respectively) into @file{@var{MY-LANGUAGE}}, then translate this
file and run @code{skeleton-update} -- see @ref{Updating documentation
translation}.  Your are now ready to translate the Notation Reference
(Application Usage, respectively) exactly like the Learning Manual.


@node Translating the Documentation index index.html.in
@unnumberedsubsubsec Translating the Documentation index @file{index.html.in}

Unlike almost all HTML pages in this documentation, links in this page
are not tweaked by @file{postprocess_html.py}, so links should be
manually edited to link to existing translations.


@node Documentation translation maintenance
@subsection Documentation translation maintenance

Several tools have been developed to make translations maintenance
easier.  These helper scripts make use of the power of Git, the
version control system used for LilyPond development.

@menu
* Check state of translation::
* Updating documentation translation::
@end menu

@node Check state of translation
@unnumberedsubsubsec Check state of translation

First pull from Git, then cd into @file{Documentation/} (or at top of
the source tree, replace @command{make} with @command{make -C
Documentation}) and run

@example
make ISOLANG=@var{MY_LANGUAGE} check-translation
@end example

@noindent
This presents a diff of the original files since the most recent
revision of the translation.  To check a single file, cd into
@file{Documentation/} and run

@example
make CHECKED_FILES=@var{MY_LANGUAGE}/@var{manual}/@var{foo}.itely check-translation
@end example

@noindent
In case this file has been renamed since you last updated the
translation, you should specify both old and new file names,
e.g. @code{CHECKED_FILES=@var{MY_LANGUAGE}/@{@var{manual},user@}/@var{foo}.itely}.

To see only which files need to be updated, do

@example
make ISOLANG=@var{MY_LANGUAGE} check-translation | grep 'diff --git'
@end example

To avoid printing terminal colors control characters, which is often
desirable when you redirect output to a file, run

@example
make ISOLANG=@var{MY_LANGUAGE} NO_COLOR=1 check-translation
@end example

Global state of the translation is recorded in
@file{Documentation/translations.html.in}, which is used to generate
Translations status page.  To update that page, do from
@file{Documentation/}

@example
make translation-status
@end example

This will also leave @file{out/translations-status.txt}, which contains
up-to-dateness percentages for each translated file, and update word
counts of documentation files in this Guide.

@seealso
@ref{Maintaining without updating translations}.


@node Updating documentation translation
@unnumberedsubsubsec Updating documentation translation

Instead of running @code{check-translation}, you may want to run
@code{update-translation}, which will run your favorite text editor to
update files.  First, make sure environment variable @code{EDITOR} is
set to a text editor command, then run from @file{Documentation/}

@example
make ISOLANG=@var{MY_LANGUAGE} update-translation
@end example

@noindent
or to update a single file

@example
make CHECKED_FILES=@var{MY_LANGUAGE/@var{manual}/foo.itely} update-translation
@end example

For each file to be udpated, @code{update-translation} will open your
text editor with this file and a diff of the file in English; if the
diff cannot be generated or is bigger than the file in English itself,
the full file in English will be opened instead.

Texinfo skeleton files, i.e. @file{.itely} files not yet translated,
containing only the Texinfo structure can be updated automatically:
whenever @command{make check-translation} shows that such files should
be updated, run from @file{Documentation/}

@example
make ISOLANG=@var{MY_LANGUAGE} skeleton-update
@end example

@file{.po} message catalogs in @file{Documentation/po/} may be updated
by issuing from @file{Documentation/} or @file{Documentation/po/}

@example
make po-update
@end example

@warning{if you run po-update and somebody else does the same and
pushes before you push or send a patch to be applied, there will be a
conflict when you pull.  Therefore, it is better that only the
Translation meister runs this command.}

Updating music snippets can quickly become cumbersome, as most
snippets should be identical in all languages.  Fortunately, there is
a script that can do this odd job for you (run from
@file{Documentation/}):

@example
make ISOLANG=@var{MY_LANGUAGE} snippet-update
@end example

This script overwrites music snippets in
@file{@var{MY_LANGUAGE/foo/every.itely}} with music snippets from
@file{@var{foo/every.itely}}.  It ignores skeleton files, and keeps
intact music snippets preceded with a line starting with @code{@@c
KEEP LY}; it reports an error for each @file{.itely} that has not the
same music snippet count in both languages.  Always use this script
with a lot of care, i.e. run it on a clean Git working tree, and check
the changes it made with @command{git diff} before committing; if you
don't do so, some @code{@@lilypond} snippets might be broken or make
no sense in their context.

When you have updated texidocs in
@file{Documentation/@var{MY-LANGUAGE}/texidocs}, you can get these
changes into compiled snippets in @file{Documentation/snippets}, see
@q{General guidelines} in @ref{Adding and editing snippets}.

Finally, a command runs the three update processes above for all
enabled languages (from @file{Documentation/}):

@example
make all-translations-update
@end example

Use this command with caution, and keep in mind it will not be really
useful until translations are stabilized after the end of GDP and GOP.

@seealso
@ref{Maintaining without updating translations},
@ref{Adding and editing snippets}.


@node Translations management policies
@subsection Translations management policies

These policies show the general intent of how the translations should
be managed, they aim at helping translators, developers and
coordinators work efficiently.

@menu
* Maintaining without updating translations::
* Managing documentation translation with Git::
@end menu

@node Maintaining without updating translations
@unnumberedsubsubsec Maintaining without updating translations

Keeping translations up to date under heavy changes in the documentation
in English may be almost impossible, especially as during the former
Grand Documentation Project (GDP) or the Grand Organization Project
(GOP) when a lot of contributors brings changes.  In addition,
translators may be --- and that is a very good thing --- involved in
these projects too.

it is possible --- and even recommended --- to perform some maintenance
that keeps translated documentation usable and eases future translation
updating.  The rationale below the tasks list motivates this plan.

The following tasks are listed in decreasing priority order.

@enumerate
@item Update macros.itexi.
For each obsolete macro definition, if it is possible to update macro
usage in documentation with an automatic text or regexp substitution,
do it and delete the macro definition from macros.itexi; otherwise,
mark this macro definition as obsolete with a comment, and keep it in
macros.itexi until the documentation translation has been updated and
no longer uses this macro.

@item Update @file{*.tely} files completely with
@command{make check-translation} -- you may want to redirect ouptput
to a file because of overwhelming output, or call check-translation.py
on individual files, see @ref{Check state of translation}.

@item In @file{.itelys}, match sections and .itely file names with those from
English docs, which possibly involves moving nodes contents in block
between files, without updating contents itself.  In other words, the
game is catching where has gone each section.  In Learning manual, and
in Notation Reference sections which have been revised in GDP, there may
be completely new sections: in this case, copy @code{@@node} and
@code{@@section}-command from English docs, and add the marker for
untranslated status @code{@@untranslated} on a single line.  Note that
it is not possible to exactly match subsections or subsubsections of
documentation in English, when contents has been deeply revised; in this
case, keep obsolete (sub)subsections in the translation, marking them
with a line @code{@@c obsolete} just before the node.

Emacs with Texinfo mode makes this step easier:

@itemize
@item without Emacs AucTeX installed, @key{C-c C-s} shows structure of current
Texinfo file in a new buffer @code{*Occur*}; to show structure of two files
simultaneously, first split Emacs window in 4 tiles (with @key{C-x 1}
and @key{C-x 2}), press @key{C-c C-s} to show structure of one file
(e.g. the translated file), copy @code{*Occur*} contents into
@code{*Scratch*}, then press @key{C-c C-s} for the other file.

If you happen to have installed AucTeX, you can either call the macro
by doing @key{M-x texinfo-show-structure} or create a key binding in your
@file{~/.emacs}, by adding the four following lines:

@example
(add-hook 'Texinfo-mode-hook
          '(lambda ()
             (define-key Texinfo-mode-map "\C-cs"
              'texinfo-show-structure)))
@end example

@noindent
and then obtain the structure in the @code{*Occur*} buffer with @key{C-c
s}.

@item Do not bother updating @code{@@menu}s when all menu entries are in the same
file, just do @key{C-c C-u C-a} (@qq{update all menus}) when you have
updated all the rest of the file.

@item Moving to next or previous node using incremental search: press
@key{C-s} and type @code{node} (or @key{C-s @@node} if the text
contains the word @q{node}) then press @key{C-s} to move to next node
or @key{C-r} to move to previous node.  Similar operation can be used
to move to the next/previous section.  Note that every cursor move
exits incremental search, and hitting @key{C-s} twice starts
incremental search with the text entered in previous incremental
search.

@item Moving a whole node (or even a sequence of nodes): jump to beginning
of the node (quit incremental search by pressing an arrow), press
@key{C-SPACE}, press @key{C-s node} and repeat @key{C-s} until you
have selected enough text, cut it with @key{C-w} or @key{C-x}, jump to
the right place (moving between nodes with the previous hint is often
useful) and paste with @key{C-y} or @key{C-v}.
@end itemize

@item Update sections finished in the English documentation; check
sections status at
@uref{http://lilypondwiki.tuxfamily.org/index.php?title=Documentation_coordination}.

@item Update documentation PO.  It is recommended not to update
strings which come from documentation that is currently deeply revised
in English, to avoid doing the work more than once.

@item Fix broken cross-references by running (from @file{Documentation/})

@example
make ISOLANG=@var{YOUR-LANGUAGE} fix-xrefs
@end example

@noindent
This step requires a sucessful documentation build (with @command{make
doc}).  Some cross-references are broken because they point to a node
that exists in the documentation in English, which has not been added
to the translation; in this case, do not fix the cross-reference but
keep it "broken", so that the resulting HTML link will point to an
existing page of documentation in English.
@end enumerate

@subsubheading Rationale

You may wonder if it would not be better to leave translations as-is
until you can really start updating translations.  There are several
reasons to do these maintenance tasks right now.

@itemize
@item This will have to be done sooner or later anyway, before updating
translation of documentation contents, and this can already be done
without needing to be redone later, as sections of documentation in
English are mostly revised once.  However, note that not all
documentation sectioning has been revised in one go, so all this
maintenance plan has to be repeated whenever a big reorganization is
made.

@item This just makes translated documentation take advantage of the new
organization, which is better than the old one.

@item Moving and renaming sections to match sectioning of documentation in
English simplify future updating work: it allows updating the
translation by side-by-side comparison, without bothering whether
cross-reference names already exist in the translation.

@item Each maintenance task except @q{Updating PO files} can be done by
the same person for all languages, which saves overall time spent by
translators to achieve this task: the node names and section titles
are in English, so you can do.  It is important to take advantage of
this now, as it will be more complicated (but still possible) to do
step 3 in all languages when documentation is compiled with
@command{texi2html} and node names are directly translated in source
files.
@end itemize


@node Managing documentation translation with Git
@unnumberedsubsubsec Managing documentation translation with Git

This policy explains how to manage Git branches and commit
translations to Git.

@itemize
@item Translation changes matching master branch are preferably made on
@code{lilypond/translation} branch; they may be pushed directly to
@code{master} only if they do not break compilation of LilyPond and
its documentation, and in this case they should be pushed to
@code{lilypond/translation} too.  Similarly, changes matching
@code{stable/X.Y} are preferably made on
@code{lilypond/X.Ytranslation}.

@item @code{lilypond/translation} Git branch may be merged into
master only if LilyPond (@command{make all}) and documentation
(@command{make doc}) compile succesfully.

@item @code{master} Git branch may be merged into
@code{lilypond/translation} whenever @command{make} and @command{make
doc} are succesful (in order to ease documentation compilation by
translators), or when significant changes had been made in
documentation in English in master branch.

@item General maintenance may be done by anybody who knows what he does
in documentation in all languages, without informing translators
first.  General maintenance include simple text substitutions
(e.g. automated by sed), compilation fixes, updating Texinfo or
lilypond-book commands, updating macros, updating ly code, fixing
cross-references, and operations described in @ref{Maintaining
without updating translations}.
@end itemize


@node Technical background
@subsection Technical background

A number of Python scripts handle a part of the documentation
translation process.  All scripts used to maintain the translations
are located in @file{scripts/auxiliar/}.

@itemize
@item @file{check_translation.py}  -- show diff to update a translation,
@item @file{texi-langutils.py}  -- quickly and dirtily parse Texinfo files to
make message catalogs and Texinfo skeleton files,
@item @file{texi-skeleton-update.py} -- update Texinfo skeleton files,
@item @file{update-snippets.py} -- synchronize ly snippets with those
from English docs,
@item @file{translations-status.py} -- update translations status pages and word
counts in the file you are reading,
@item @file{tely-gettext.py} -- gettext node names, section titles and references
in the sources; WARNING only use this script once for each file, when support for
"makeinfo --html" has been dropped.
@end itemize

Other scripts are used in the build process, in @file{scripts/build/}:

@itemize
@item @file{mass-link.py} -- link or symlink files between English documentation
and documentation in other languages.
@end itemize

Python modules used by scripts in @file{scripts/auxiliar/} or @file{scripts/build/} (but
not by installed Python scripts) are located in @file{python/auxiliar/}:
@itemize
@item @file{manuals_definitions.py} -- define manual names and name of
cross-reference Texinfo macros,
@item @file{buildlib.py} -- common functions (read piped output
of a shell command, use Git),
@item @file{postprocess_html.py} (module imported by @file{www_post.py}) -- add footer and
tweak links in HTML pages.
@end itemize

And finally
@itemize
@item @file{python/langdefs.py}  -- language definitions module
@end itemize