[dconf-editor] Add the reference DTD.

[Arnaud Bonatti <arnaudb src gnome org>]

commit d680cd11a3b5cd1a826fe62edb4d833bd5b19e6c
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Tue Dec 5 14:47:38 2017 +0100

    Add the reference DTD.

 editor/ca.desrt.dconf-editor.gschema.xml |   81 ++++++++++++++++++++++++++++++
 1 files changed, 81 insertions(+), 0 deletions(-)
---
diff --git a/editor/ca.desrt.dconf-editor.gschema.xml b/editor/ca.desrt.dconf-editor.gschema.xml
index 51d280a..f928d5c 100644
--- a/editor/ca.desrt.dconf-editor.gschema.xml
+++ b/editor/ca.desrt.dconf-editor.gschema.xml
@@ -1,4 +1,85 @@
 <?xml version="1.0" encoding="UTF-8"?>
+<!--
+  https://git.gnome.org/browse/glib/log/gio/gschema.dtd
+  /usr/share/glib-2.0/schemas/gschema.dtd
+-->
+<!DOCTYPE schemalist [
+  <!ELEMENT schemalist (schema|enum|flags)* >
+  <!ATTLIST schemalist gettext-domain CDATA #IMPLIED >
+
+  <!ELEMENT schema (key|child|override)* >
+  <!ATTLIST schema id             CDATA #REQUIRED
+                   path           CDATA #IMPLIED
+                   gettext-domain CDATA #IMPLIED
+                   extends        CDATA #IMPLIED
+                   list-of        CDATA #IMPLIED >
+
+  <!-- enumerated and flags types -->
+  <!-- each value element maps a nick to a numeric value -->
+  <!ELEMENT enum (value*) >
+  <!ATTLIST enum id CDATA #REQUIRED >
+
+  <!ELEMENT flags (value*) >
+  <!ATTLIST flags id CDATA #REQUIRED >
+
+  <!ELEMENT value EMPTY >
+  <!-- nick must be at least 2 characters long -->
+  <!-- value must be parsable as a 32-bit integer -->
+  <!ATTLIST value nick  CDATA #REQUIRED
+                  value CDATA #REQUIRED >
+
+  <!ELEMENT key (default|summary?|description?|range?|choices?|aliases?)* >
+  <!-- name can only contain lowercase letters, numbers and '-' -->
+  <!-- type must be a GVariant type string -->
+  <!-- enum must be the id of an enum type that has been defined earlier -->
+  <!-- flags must be the id of a flags type that has been defined earlier -->
+  <!-- exactly one of type, enum or flags must be given -->
+  <!ATTLIST key name  CDATA #REQUIRED
+                type  CDATA #IMPLIED
+                enum  CDATA #IMPLIED
+                flags CDATA #IMPLIED >
+
+  <!-- the default value is specified a a serialized GVariant,
+       i.e. you have to include the quotes when specifying a string -->
+  <!ELEMENT default (#PCDATA) >
+  <!-- the presence of the l10n attribute marks a default value for
+       translation, its value is the gettext category to use -->
+  <!-- if context is present, it specifies msgctxt to use -->
+  <!ATTLIST default l10n    (messages|time) #IMPLIED
+                    context CDATA           #IMPLIED >
+
+  <!ELEMENT summary (#PCDATA) >
+  <!ELEMENT description (#PCDATA) >
+
+  <!-- range is only allowed for keys with numeric type -->
+  <!ELEMENT range EMPTY >
+  <!-- min and max must be parseable as values of the key type and -->
+  <!-- min less-than or equal to max -->
+  <!ATTLIST range min CDATA #REQUIRED
+                  max CDATA #REQUIRED >
+
+  <!-- choices is only allowed for keys with string or string array type -->
+  <!ELEMENT choices (choice+) >
+  <!-- each choice element specifies one possible value -->
+  <!ELEMENT choice EMPTY >
+  <!ATTLIST choice value CDATA #REQUIRED >
+
+  <!-- aliases is only allowed for keys with enumerated type or with choices -->
+  <!ELEMENT aliases (alias+) >
+  <!-- each alias element specifies an alias for one of the possible values -->
+  <!ELEMENT alias EMPTY >
+  <!ATTLIST alias value CDATA #REQUIRED >
+
+  <!ELEMENT child EMPTY >
+  <!ATTLIST child name   CDATA #REQUIRED
+                  schema CDATA #REQUIRED >
+
+  <!ELEMENT override (#PCDATA) >
+  <!ATTLIST override name    CDATA #REQUIRED
+                     l10n    CDATA #IMPLIED
+                     context CDATA #IMPLIED >
+]>
+
 <schemalist gettext-domain='dconf-editor'>
   <!-- enum id="ca.desrt.dconf-editor.Themes">
     <value value="0" nick="three-twenty-two"/>