1. Introduction
  The GIMP documentation project is mainly working with docbook xml files
  to create the GIMP manual / online help.  Since there are different
  approaches how to create and edit such files as well as different tools
  involved, there is a strong need for the xml files being well formated.
  Additionally there are a couple of technical reasons (diff, cvs) that
  suggest a general styleguide for the xml files.  This is a recommendation
  for such a styleguide. Its mainly based on the styles that can be found
  in xml files that build the current documentation, as well as on the
  discussion on the gimp-doc mailing list.

2. XML styleguide by rules
  §1. General
  §1.1. All docbook files for the documentation need to be well formed and
    have to comply validation against
    http://www.docbook.org/xml/4.3/docbookx.dtd.
  §1.2. All docbook files use UTF-8 character encoding.

  §2. Length of lines
  §2.1. The length of line should not exceed 78 characters. Exceptions
    might be made for text that is technically not able to be wrapped
    (chinese text does rarely contain space characters, so it can't be
    wrapped without introducing unwanted whitespaces) and attributes of
    elements.

  §3. Elements and new lines
  §3.1. Element tagnames are written lowercase completely
  §3.2. All tags (opening and closing) are starting a new line. For
    exceptions see §3.3
  §3.3. Elements listed in Appendix I (inline elements) do not have the
    opening and closing tags on new lines, as long as their content does not
    exceed 78 characters.

  §4. Element attributes
  §4.1. Element attributes are written completely lowercase
  §4.2. Element attributes values are enclosed in double quotes ( " )
  §4.3. The languages encoded in the lang attributes appear in alphabetical
    order of the language codes

  §5. Indention
  §5.1. Space or tab characters can be used for indentation, but it is higly
    recommended not to mix space and tab character usage in one single xml
    file.
  §5.2. Indention width is two spaces (0x20). One tab (0x09) is equivalent
    to 8 spaces (0x20).
  §5.3. Indention is done for the content of all tags that start a new line

2 XML styleguide by example
  Example for §1 General
  Following the rules in §1 each xml file of the GIMP manual starts with:

  <?xml version='1.0' encoding='UTF-8'?>
  <!DOCTYPE abcd
  PUBLIC '-//OASIS//DTD DocBook XML V4.3//EN'
  'http://www.docbook.org/xml/4.3/docbookx.dtd'>

  where abcd is the root element of the file (usually book, sect1 of sect2).

  Example for §2. Length of lines
  // to be done

  Example for §3. Elements and new lines
  // to be done

  Example for §4. Element attributes
  // to be done

  Example for §5. Indention
  // to be done

Appendix I Inline elements
  <abbrev>
  <accel>
  <acronym>
  <action>
  <anchor>
  <application>
  <citation>
  <citerefentry>
  <citetitle>
  <classname>
  <command>
  <computeroutput>
  <constant>
  <database>
  <email>
  <emphasis>
  <envar>
  <errorcode>
  <errorname>
  <filename>
  <firstterm>
  <footnote>
  <forignphrase>
  <function>
  <guibutton>
  <guiicon>
  <guilabel>
  <guimenu>
  <guimenuitem>
  <guisubmenu>
  <glossterm>
  <hardware>
  <inlineequation>
  <inlinegraphic>
  <interface>
  <interfacedefinition>
  <keycap>
  <keycode>
  <keycombo>
  <keysym>
  <link>
  <literal>
  <markup>
  <medialabel>
  <menuchoice>
  <mousebutton>
  <msgtext>
  <olink>
  <option>
  <optional>
  <parameter>
  <phrase>
  <prompt>
  <property>
  <quote>
  <replacable>
  <returnvalue>
  <shortcut>
  <structfield>
  <structname>
  <subsrcipt>
  <superscript>
  <symbol>
  <systemitem>
  <token>
  <trademark>
  <type>
  <ulink>
  <userinput>
  <varname>
  <wordasword>
  <xref>