New `xml` format exactly representing a Pandoc AST.

This adds a reader and writer for an XML format equivalent to `native`
and `json`.

XML schemas for validation can be found in `tools/pandoc-xml.*`.

The format is documented in `doc/xml.md`.

API changes:

- Add module Text.Pandoc.Readers.XML, exporting `readXML`.
- Add module Text.Pandoc.Writers.XML, exporting `writeXML`.

A new unexported module Text.Pandoc.XMLFormat is also added.

4 files changed, 1946 insertions, 0 deletions

diff --git a/tools/pandoc-xml.dtd b/tools/pandoc-xml.dtd
new file mode 100644
index 000000000..e787596ed
--- /dev/null
+++ b/tools/pandoc-xml.dtd
@@ -0,0 +1,181 @@
+<!--
+A DTD for Pandoc XML format.
+Copyright   : Copyright (C) 2025- Massimiliano Farinella
+License     : GNU GPL, version 2 or above
+Maintainer  : Massimiliano Farinella <[email protected]>
+
+This is a DTD for the XML representation of Pandoc AST.
+It's an equivalent of native and JSON formats, but modeled as XML.
+You can validate Pandoc XML documents with this DTD,
+but there are some limitations:
+- a Pandoc Attr can contain arbitrary attributes, but it looks like you can't tell
+  an element has arbitrary attributes in a DTD
+- some Pandoc attributes have constraints that can't be specified with a DTD
+The Relax-NG and XML Schema translations of this specification overcome
+some of those limitations (see pandoc-xml.rng and pandoc-xml.xsd).
+-->
+<!ELEMENT Pandoc (meta, blocks)>
+<!ATTLIST Pandoc api-version CDATA #REQUIRED>
+
+<!ENTITY % block "Para | Plain | Header | Div | BlockQuote | HorizontalRule | BulletList | OrderedList | DefinitionList | Table | Figure | LineBlock | CodeBlock | RawBlock">
+
+<!ENTITY % inline_element "Str | Space | Emph | Strong | Underline | Strikeout | Superscript | Subscript | SmallCaps | Quoted | Cite | Code | SoftBreak | LineBreak | Math | RawInline | Link | Image | Note | Span">
+<!ENTITY % inline "#PCDATA | %inline_element;">
+
+<!ENTITY % attr "id ID #IMPLIED class CDATA #IMPLIED">
+
+<!ENTITY % metavalue "MetaMap | MetaList | MetaBool | MetaString | MetaInlines | MetaBlocks">
+
+<!ELEMENT meta (entry*)>
+<!ELEMENT MetaMap (entry*)>
+
+<!ELEMENT entry (%metavalue;)*>
+<!ATTLIST entry key CDATA #REQUIRED>
+
+<!ELEMENT MetaList (%metavalue;)*>
+
+<!ELEMENT MetaBool EMPTY>
+<!ATTLIST MetaBool value (true | false) #REQUIRED>
+
+<!ELEMENT MetaString (#PCDATA)>
+
+<!ELEMENT MetaInlines (%inline;)*>
+
+<!ELEMENT MetaBlocks (%block;)*>
+
+<!ELEMENT blocks (%block;)*>
+
+<!ELEMENT Para (%inline;)*>
+
+<!ELEMENT Plain (%inline;)*>
+
+<!ELEMENT Header (%inline;)*>
+<!ATTLIST Header
+  level CDATA "1"
+  %attr;>
+
+<!ELEMENT Div (%block;)* >
+<!ATTLIST Div
+  custom-style CDATA #IMPLIED
+  %attr;>
+
+<!ELEMENT BlockQuote (%block;)*>
+
+<!ELEMENT HorizontalRule EMPTY>
+
+<!ELEMENT BulletList (item)+>
+
+<!ELEMENT OrderedList (item)+>
+<!ATTLIST OrderedList
+  start CDATA "1"
+  number-style (DefaultStyle | Example | Decimal | LowerRoman | UpperRoman | LowerAlpha | UpperAlpha) "DefaultStyle"
+  number-delim (DefaultDelim | Period | OneParen | TwoParens) "DefaultDelim">
+
+<!ELEMENT DefinitionList (item)+>
+
+<!ELEMENT item ((%block;)*|(term,def+))>
+<!ELEMENT term (%inline;)*>
+<!ELEMENT def (%block;)*>
+
+<!ELEMENT Table (Caption, colspecs, TableHead, TableBody+, TableFoot)>
+<!ATTLIST Table
+  custom-style CDATA #IMPLIED
+  %attr;>
+<!ELEMENT Caption (ShortCaption?, (%block;)*)>
+<!ELEMENT ShortCaption (%inline;)*>
+<!ELEMENT colspecs (ColSpec+)>
+<!ELEMENT ColSpec EMPTY>
+<!ATTLIST ColSpec
+  alignment (AlignLeft | AlignRight | AlignCenter | AlignDefault) "AlignDefault"
+  col-width CDATA "0">
+<!ELEMENT TableHead (Row*)>
+<!ATTLIST TableHead %attr;>
+<!ELEMENT TableFoot (Row*)>
+<!ATTLIST TableFoot %attr;>
+<!ELEMENT TableBody (header, body)>
+<!ATTLIST TableBody
+  row-head-columns CDATA "0"
+  %attr;>
+<!ELEMENT header (Row*)>
+<!ELEMENT body (Row*)>
+<!ELEMENT Row (Cell*)>
+<!ATTLIST Row %attr;>
+<!ELEMENT Cell (%block;)*>
+<!ATTLIST Cell
+  alignment (AlignLeft | AlignRight | AlignCenter | AlignDefault) "AlignDefault"
+  row-span CDATA "1"
+  col-span CDATA "1"
+  %attr; >
+
+<!ELEMENT Figure (Caption,(%block;)*)>
+<!ATTLIST Figure %attr;>
+
+<!ELEMENT LineBlock (line+)>
+<!ELEMENT line (%inline;)*>
+
+<!ELEMENT CodeBlock (#PCDATA)>
+<!ATTLIST CodeBlock %attr;>
+
+<!ELEMENT RawBlock (#PCDATA)>
+<!ATTLIST RawBlock format CDATA #REQUIRED>
+
+<!ELEMENT Space EMPTY>
+<!ATTLIST Space count CDATA "1">
+
+<!ELEMENT Str EMPTY>
+<!ATTLIST Str content CDATA "">
+
+<!ELEMENT Emph (%inline;)*>
+<!ELEMENT Strong (%inline;)*>
+<!ELEMENT Underline (%inline;)*>
+<!ELEMENT Strikeout (%inline;)*>
+<!ELEMENT Superscript (%inline;)*>
+<!ELEMENT Subscript (%inline;)*>
+<!ELEMENT SmallCaps (%inline;)*>
+
+<!ELEMENT Span (%inline;)*>
+<!ATTLIST Span
+  custom-style CDATA #IMPLIED
+  %attr;>
+
+<!ELEMENT Quoted (%inline;)*>
+<!ATTLIST Quoted quote-type (SingleQuote | DoubleQuote) "DoubleQuote">
+
+<!ELEMENT Math (#PCDATA)>
+<!ATTLIST Math math-type (DisplayMath	| InlineMath) "InlineMath">
+
+<!ELEMENT RawInline (#PCDATA)>
+<!ATTLIST RawInline format CDATA #REQUIRED>
+
+<!ELEMENT Cite (#PCDATA | citations | %inline_element;)*>
+<!ELEMENT citations (Citation)+>
+<!ELEMENT Citation (prefix?, suffix?)>
+<!ELEMENT prefix (%inline;)*>
+<!ELEMENT suffix (%inline;)*>
+<!ATTLIST Citation
+  id CDATA #IMPLIED
+  note-num CDATA #IMPLIED
+  hash CDATA "0"
+  mode (AuthorInText	| SuppressAuthor | NormalCitation) "AuthorInText">
+
+<!ELEMENT Code (#PCDATA)>
+<!ATTLIST Code %attr;>
+
+<!ENTITY % target "title CDATA #IMPLIED url CDATA #IMPLIED">
+
+<!ELEMENT Image (%inline;)*>
+<!ATTLIST Image
+  title CDATA #IMPLIED
+  src CDATA #IMPLIED
+  %attr;>
+
+<!ELEMENT Link (%inline;)*>
+<!ATTLIST Link
+  title CDATA #IMPLIED
+  href CDATA #IMPLIED
+  %attr;>
+
+<!ELEMENT SoftBreak EMPTY>
+<!ELEMENT LineBreak EMPTY>
+
+<!ELEMENT Note (%block;)*>
diff --git a/tools/pandoc-xml.rnc b/tools/pandoc-xml.rnc
new file mode 100644
index 000000000..59043d650
--- /dev/null
+++ b/tools/pandoc-xml.rnc
@@ -0,0 +1,250 @@
+# A RELAX NG schema for Pandoc XML format.
+# Copyright   : Copyright (C) 2025- Massimiliano Farinella
+# License     : GNU GPL, version 2 or above
+# Maintainer  : Massimiliano Farinella <[email protected]>
+# 
+# This is a RELAX NG schema for the XML representation of Pandoc AST.
+# It's an equivalent of native and JSON formats, but modeled as XML.
+# You can use this schema to validate Pandoc XML documents.
+# It's translated from pandoc-xml.dtd with the "Trang" software by James Clark,
+# and adjusted manually to add some constraints:
+# - elements with Attr can have arbitrary attributes (this is not possible with a DTD)
+# - Header's "level", OrderedList's "start" and Cell's "rowspan" and "colspan" attributes
+#   must be a positive integer and are equal to 1 if not specified
+# - column widths in ColSpec must be between 0 and 1 (inclusive, with 0=ColWidthDefault)
+# - the "count" attribute in the "<Space>" element must be positive and equal to 1 if not specified
+
+namespace a = "http://relaxng.org/ns/compatibility/annotations/1.0"
+
+Pandoc = element Pandoc { attlist_Pandoc, meta, blocks }
+attlist_Pandoc &= attribute api-version { text }
+block =
+  Para
+  | Plain
+  | Header
+  | Div
+  | BlockQuote
+  | HorizontalRule
+  | BulletList
+  | OrderedList
+  | DefinitionList
+  | Table
+  | Figure
+  | LineBlock
+  | CodeBlock
+  | RawBlock
+inline_element =
+  Str
+  | Space
+  | Emph
+  | Strong
+  | Underline
+  | Strikeout
+  | Superscript
+  | Subscript
+  | SmallCaps
+  | Quoted
+  | Cite
+  | Code
+  | SoftBreak
+  | LineBreak
+  | Math
+  | RawInline
+  | Link
+  | Image
+  | Note
+  | Span
+inline = text | inline_element
+attr =
+  attribute id { xsd:ID }?,
+  attribute class { text }?,
+  attribute * { text }*
+metavalue =
+  MetaMap | MetaList | MetaBool | MetaString | MetaInlines | MetaBlocks
+meta = element meta { attlist_meta, entry* }
+attlist_meta &= empty
+MetaMap = element MetaMap { attlist_MetaMap, entry* }
+attlist_MetaMap &= empty
+entry = element entry { attlist_entry, metavalue* }
+attlist_entry &= attribute key { text }
+MetaList = element MetaList { attlist_MetaList, metavalue* }
+attlist_MetaList &= empty
+MetaBool = element MetaBool { attlist_MetaBool, empty }
+attlist_MetaBool &= attribute value { "true" | "false" }
+MetaString = element MetaString { attlist_MetaString, text }
+attlist_MetaString &= empty
+MetaInlines = element MetaInlines { attlist_MetaInlines, inline* }
+attlist_MetaInlines &= empty
+MetaBlocks = element MetaBlocks { attlist_MetaBlocks, block* }
+attlist_MetaBlocks &= empty
+blocks = element blocks { attlist_blocks, block* }
+attlist_blocks &= empty
+Para = element Para { attlist_Para, inline* }
+attlist_Para &= empty
+Plain = element Plain { attlist_Plain, inline* }
+attlist_Plain &= empty
+Header = element Header { attlist_Header, inline* }
+attlist_Header &=
+  [ a:defaultValue = "1" ] attribute level { xsd:positiveInteger }?,
+  attr
+Div = element Div { attlist_Div, block* }
+attlist_Div &= attr
+BlockQuote = element BlockQuote { attlist_BlockQuote, block* }
+attlist_BlockQuote &= empty
+HorizontalRule =
+  element HorizontalRule { attlist_HorizontalRule, empty }
+attlist_HorizontalRule &= empty
+BulletList = element BulletList { attlist_BulletList, item+ }
+attlist_BulletList &= empty
+OrderedList = element OrderedList { attlist_OrderedList, item+ }
+attlist_OrderedList &=
+  [ a:defaultValue = "1" ] attribute start { xsd:positiveInteger }?,
+  [ a:defaultValue = "DefaultStyle" ]
+  attribute number-style {
+    "DefaultStyle"
+    | "Example"
+    | "Decimal"
+    | "LowerRoman"
+    | "UpperRoman"
+    | "LowerAlpha"
+    | "UpperAlpha"
+  }?,
+  [ a:defaultValue = "DefaultDelim" ]
+  attribute number-delim {
+    "DefaultDelim" | "Period" | "OneParen" | "TwoParens"
+  }?
+DefinitionList =
+  element DefinitionList { attlist_DefinitionList, item+ }
+attlist_DefinitionList &= empty
+item =
+  element item {
+    attlist_item,
+    (block* | (term, def+))
+  }
+attlist_item &= empty
+term = element term { attlist_term, inline* }
+attlist_term &= empty
+def = element def { attlist_def, block* }
+attlist_def &= empty
+Table =
+  element Table {
+    attlist_Table, Caption, colspecs, TableHead, TableBody+, TableFoot
+  }
+attlist_Table &= attr
+Caption = element Caption { attlist_Caption, ShortCaption?, block* }
+attlist_Caption &= empty
+ShortCaption = element ShortCaption { attlist_ShortCaption, inline* }
+attlist_ShortCaption &= empty
+colspecs = element colspecs { attlist_colspecs, ColSpec+ }
+attlist_colspecs &= empty
+ColSpec = element ColSpec { attlist_ColSpec, empty }
+attlist_ColSpec &=
+  [ a:defaultValue = "AlignDefault" ]
+  attribute alignment {
+    "AlignLeft" | "AlignRight" | "AlignCenter" | "AlignDefault"
+  }?,
+  [ a:defaultValue = "0" ]
+  attribute col-width {
+    xsd:double { minInclusive = "0" maxInclusive = "1" }
+  }?
+TableHead = element TableHead { attlist_TableHead, Row* }
+attlist_TableHead &= attr
+TableFoot = element TableFoot { attlist_TableFoot, Row* }
+attlist_TableFoot &= attr
+TableBody = element TableBody { attlist_TableBody, header, body }
+attlist_TableBody &=
+  [ a:defaultValue = "0" ] attribute row-head-columns { text }?,
+  attr
+header = element header { attlist_header, Row* }
+attlist_header &= empty
+body = element body { attlist_body, Row* }
+attlist_body &= empty
+Row = element Row { attlist_Row, Cell* }
+attlist_Row &= attr
+Cell = element Cell { attlist_Cell, block* }
+attlist_Cell &=
+  [ a:defaultValue = "AlignDefault" ]
+  attribute alignment {
+    "AlignLeft" | "AlignRight" | "AlignCenter" | "AlignDefault"
+  }?,
+  [ a:defaultValue = "1" ] attribute row-span { xsd:positiveInteger }?,
+  [ a:defaultValue = "1" ] attribute col-span { xsd:positiveInteger }?,
+  attr
+Figure = element Figure { attlist_Figure, Caption, block* }
+attlist_Figure &= attr
+LineBlock = element LineBlock { attlist_LineBlock, line+ }
+attlist_LineBlock &= empty
+line = element line { attlist_line, inline* }
+attlist_line &= empty
+CodeBlock = element CodeBlock { attlist_CodeBlock, text }
+attlist_CodeBlock &= attr
+RawBlock = element RawBlock { attlist_RawBlock, text }
+attlist_RawBlock &= attribute format { text }
+Space = element Space { attlist_Space, empty }
+attlist_Space &=
+  [ a:defaultValue = "1" ] attribute count { xsd:positiveInteger }?
+Str = element Str { attlist_Str, empty }
+attlist_Str &= [ a:defaultValue = "" ] attribute content { text }?
+Emph = element Emph { attlist_Emph, inline* }
+attlist_Emph &= empty
+Strong = element Strong { attlist_Strong, inline* }
+attlist_Strong &= empty
+Underline = element Underline { attlist_Underline, inline* }
+attlist_Underline &= empty
+Strikeout = element Strikeout { attlist_Strikeout, inline* }
+attlist_Strikeout &= empty
+Superscript = element Superscript { attlist_Superscript, inline* }
+attlist_Superscript &= empty
+Subscript = element Subscript { attlist_Subscript, inline* }
+attlist_Subscript &= empty
+SmallCaps = element SmallCaps { attlist_SmallCaps, inline* }
+attlist_SmallCaps &= empty
+Span = element Span { attlist_Span, inline* }
+attlist_Span &= attr
+Quoted = element Quoted { attlist_Quoted, inline* }
+attlist_Quoted &=
+  [ a:defaultValue = "DoubleQuote" ]
+  attribute quote-type { "SingleQuote" | "DoubleQuote" }?
+Math = element Math { attlist_Math, text }
+attlist_Math &=
+  [ a:defaultValue = "InlineMath" ]
+  attribute math-type { "DisplayMath" | "InlineMath" }?
+RawInline = element RawInline { attlist_RawInline, text }
+attlist_RawInline &= attribute format { text }
+Cite =
+  element Cite { attlist_Cite, (text | citations | inline_element)* }
+attlist_Cite &= empty
+citations = element citations { attlist_citations, Citation+ }
+attlist_citations &= empty
+Citation = element Citation { attlist_Citation, prefix?, suffix? }
+prefix = element prefix { attlist_prefix, inline* }
+attlist_prefix &= empty
+suffix = element suffix { attlist_suffix, inline* }
+attlist_suffix &= empty
+attlist_Citation &=
+  attribute id { text }?,
+  attribute note-num { text }?,
+  [ a:defaultValue = "0" ] attribute hash { text }?,
+  [ a:defaultValue = "AuthorInText" ]
+  attribute mode {
+    "AuthorInText" | "SuppressAuthor" | "NormalCitation"
+  }?
+Code = element Code { attlist_Code, text }
+attlist_Code &= attr
+Image = element Image { attlist_Image, inline* }
+attlist_Image &=
+  attribute title { text }?,
+  attribute src { text }?,
+  attr
+Link = element Link { attlist_Link, inline* }
+attlist_Link &=
+  attribute title { text }?,
+  attribute href { text }?,
+  attr
+SoftBreak = element SoftBreak { attlist_SoftBreak, empty }
+attlist_SoftBreak &= empty
+LineBreak = element LineBreak { attlist_LineBreak, empty }
+attlist_LineBreak &= empty
+Note = element Note { attlist_Note, block* }
+attlist_Note &= empty
+start = Pandoc
diff --git a/tools/pandoc-xml.rng b/tools/pandoc-xml.rng
new file mode 100644
index 000000000..38188f781
--- /dev/null
+++ b/tools/pandoc-xml.rng
@@ -0,0 +1,913 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+A RELAX NG schema for Pandoc XML format.
+Copyright   : Copyright (C) 2025- Massimiliano Farinella
+License     : GNU GPL, version 2 or above
+Maintainer  : Massimiliano Farinella <[email protected]>
+
+This is a RELAX NG schema for the XML representation of Pandoc AST.
+It's an equivalent of native and JSON formats, but modeled as XML.
+You can use this schema to validate Pandoc XML documents.
+It's translated from pandoc-xml.dtd with the "Trang" software by James Clark,
+and adjusted manually to add some constraints:
+- elements with Attr can have arbitrary attributes (this is not possible with a DTD)
+- Header's "level", OrderedList's "start" and Cell's "rowspan" and "colspan" attributes
+  must be a positive integer and are equal to 1 if not specified
+- column widths in ColSpec must be between 0 and 1 (inclusive, with 0=ColWidthDefault)
+- the "count" attribute in the "<Space>" element must be positive and equal to 1 if not specified
+-->
+<grammar xmlns:a="http://relaxng.org/ns/compatibility/annotations/1.0"
+  xmlns="http://relaxng.org/ns/structure/1.0" datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
+  <define name="Pandoc">
+    <element name="Pandoc">
+      <ref name="attlist_Pandoc" />
+      <ref name="meta" />
+      <ref name="blocks" />
+    </element>
+  </define>
+  <define name="attlist_Pandoc" combine="interleave">
+    <attribute name="api-version" />
+  </define>
+  <define name="block">
+    <choice>
+      <ref name="Para" />
+      <ref name="Plain" />
+      <ref name="Header" />
+      <ref name="Div" />
+      <ref name="BlockQuote" />
+      <ref name="HorizontalRule" />
+      <ref name="BulletList" />
+      <ref name="OrderedList" />
+      <ref name="DefinitionList" />
+      <ref name="Table" />
+      <ref name="Figure" />
+      <ref name="LineBlock" />
+      <ref name="CodeBlock" />
+      <ref name="RawBlock" />
+    </choice>
+  </define>
+  <define name="inline_element">
+    <choice>
+      <ref name="Str" />
+      <ref name="Space" />
+      <ref name="Emph" />
+      <ref name="Strong" />
+      <ref name="Underline" />
+      <ref name="Strikeout" />
+      <ref name="Superscript" />
+      <ref name="Subscript" />
+      <ref name="SmallCaps" />
+      <ref name="Quoted" />
+      <ref name="Cite" />
+      <ref name="Code" />
+      <ref name="SoftBreak" />
+      <ref name="LineBreak" />
+      <ref name="Math" />
+      <ref name="RawInline" />
+      <ref name="Link" />
+      <ref name="Image" />
+      <ref name="Note" />
+      <ref name="Span" />
+    </choice>
+  </define>
+  <define name="inline">
+    <choice>
+      <text />
+      <ref name="inline_element" />
+    </choice>
+  </define>
+  <define name="attr">
+    <optional>
+      <attribute name="id">
+        <data type="ID" />
+      </attribute>
+    </optional>
+    <optional>
+      <attribute name="class" />
+    </optional>
+    <zeroOrMore>
+      <attribute>
+        <anyName />
+      </attribute>
+    </zeroOrMore>
+  </define>
+  <define name="metavalue">
+    <choice>
+      <ref name="MetaMap" />
+      <ref name="MetaList" />
+      <ref name="MetaBool" />
+      <ref name="MetaString" />
+      <ref name="MetaInlines" />
+      <ref name="MetaBlocks" />
+    </choice>
+  </define>
+  <define name="meta">
+    <element name="meta">
+      <ref name="attlist_meta" />
+      <zeroOrMore>
+        <ref name="entry" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_meta" combine="interleave">
+    <empty />
+  </define>
+  <define name="MetaMap">
+    <element name="MetaMap">
+      <ref name="attlist_MetaMap" />
+      <zeroOrMore>
+        <ref name="entry" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_MetaMap" combine="interleave">
+    <empty />
+  </define>
+  <define name="entry">
+    <element name="entry">
+      <ref name="attlist_entry" />
+      <zeroOrMore>
+        <ref name="metavalue" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_entry" combine="interleave">
+    <attribute name="key" />
+  </define>
+  <define name="MetaList">
+    <element name="MetaList">
+      <ref name="attlist_MetaList" />
+      <zeroOrMore>
+        <ref name="metavalue" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_MetaList" combine="interleave">
+    <empty />
+  </define>
+  <define name="MetaBool">
+    <element name="MetaBool">
+      <ref name="attlist_MetaBool" />
+      <empty />
+    </element>
+  </define>
+  <define name="attlist_MetaBool" combine="interleave">
+    <attribute name="value">
+      <choice>
+        <value>true</value>
+        <value>false</value>
+      </choice>
+    </attribute>
+  </define>
+  <define name="MetaString">
+    <element name="MetaString">
+      <ref name="attlist_MetaString" />
+      <text />
+    </element>
+  </define>
+  <define name="attlist_MetaString" combine="interleave">
+    <empty />
+  </define>
+  <define name="MetaInlines">
+    <element name="MetaInlines">
+      <ref name="attlist_MetaInlines" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_MetaInlines" combine="interleave">
+    <empty />
+  </define>
+  <define name="MetaBlocks">
+    <element name="MetaBlocks">
+      <ref name="attlist_MetaBlocks" />
+      <zeroOrMore>
+        <ref name="block" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_MetaBlocks" combine="interleave">
+    <empty />
+  </define>
+  <define name="blocks">
+    <element name="blocks">
+      <ref name="attlist_blocks" />
+      <zeroOrMore>
+        <ref name="block" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_blocks" combine="interleave">
+    <empty />
+  </define>
+  <define name="Para">
+    <element name="Para">
+      <ref name="attlist_Para" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Para" combine="interleave">
+    <empty />
+  </define>
+  <define name="Plain">
+    <element name="Plain">
+      <ref name="attlist_Plain" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Plain" combine="interleave">
+    <empty />
+  </define>
+  <define name="Header">
+    <element name="Header">
+      <ref name="attlist_Header" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Header" combine="interleave">
+    <optional>
+      <attribute name="level" a:defaultValue="1">
+        <data type="positiveInteger" />
+      </attribute>
+    </optional>
+    <ref name="attr" />
+  </define>
+  <define name="Div">
+    <element name="Div">
+      <ref name="attlist_Div" />
+      <zeroOrMore>
+        <ref name="block" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Div" combine="interleave">
+    <ref name="attr" />
+  </define>
+  <define name="BlockQuote">
+    <element name="BlockQuote">
+      <ref name="attlist_BlockQuote" />
+      <zeroOrMore>
+        <ref name="block" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_BlockQuote" combine="interleave">
+    <empty />
+  </define>
+  <define name="HorizontalRule">
+    <element name="HorizontalRule">
+      <ref name="attlist_HorizontalRule" />
+      <empty />
+    </element>
+  </define>
+  <define name="attlist_HorizontalRule" combine="interleave">
+    <empty />
+  </define>
+  <define name="BulletList">
+    <element name="BulletList">
+      <ref name="attlist_BulletList" />
+      <oneOrMore>
+        <ref name="item" />
+      </oneOrMore>
+    </element>
+  </define>
+  <define name="attlist_BulletList" combine="interleave">
+    <empty />
+  </define>
+  <define name="OrderedList">
+    <element name="OrderedList">
+      <ref name="attlist_OrderedList" />
+      <oneOrMore>
+        <ref name="item" />
+      </oneOrMore>
+    </element>
+  </define>
+  <define name="attlist_OrderedList" combine="interleave">
+    <optional>
+      <attribute name="start" a:defaultValue="1">
+        <data type="positiveInteger" />
+      </attribute>
+    </optional>
+    <optional>
+      <attribute name="number-style" a:defaultValue="DefaultStyle">
+        <choice>
+          <value>DefaultStyle</value>
+          <value>Example</value>
+          <value>Decimal</value>
+          <value>LowerRoman</value>
+          <value>UpperRoman</value>
+          <value>LowerAlpha</value>
+          <value>UpperAlpha</value>
+        </choice>
+      </attribute>
+    </optional>
+    <optional>
+      <attribute name="number-delim" a:defaultValue="DefaultDelim">
+        <choice>
+          <value>DefaultDelim</value>
+          <value>Period</value>
+          <value>OneParen</value>
+          <value>TwoParens</value>
+        </choice>
+      </attribute>
+    </optional>
+  </define>
+  <define name="DefinitionList">
+    <element name="DefinitionList">
+      <ref name="attlist_DefinitionList" />
+      <oneOrMore>
+        <ref name="item" />
+      </oneOrMore>
+    </element>
+  </define>
+  <define name="attlist_DefinitionList" combine="interleave">
+    <empty />
+  </define>
+  <define name="item">
+    <element name="item">
+      <ref name="attlist_item" />
+      <choice>
+        <zeroOrMore>
+          <ref name="block" />
+        </zeroOrMore>
+        <group>
+          <ref name="term" />
+          <oneOrMore>
+            <ref name="def" />
+          </oneOrMore>
+        </group>
+      </choice>
+    </element>
+  </define>
+  <define name="attlist_item" combine="interleave">
+    <empty />
+  </define>
+  <define name="term">
+    <element name="term">
+      <ref name="attlist_term" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_term" combine="interleave">
+    <empty />
+  </define>
+  <define name="def">
+    <element name="def">
+      <ref name="attlist_def" />
+      <zeroOrMore>
+        <ref name="block" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_def" combine="interleave">
+    <empty />
+  </define>
+  <define name="Table">
+    <element name="Table">
+      <ref name="attlist_Table" />
+      <ref name="Caption" />
+      <ref name="colspecs" />
+      <ref name="TableHead" />
+      <oneOrMore>
+        <ref name="TableBody" />
+      </oneOrMore>
+      <ref name="TableFoot" />
+    </element>
+  </define>
+  <define name="attlist_Table" combine="interleave">
+    <ref name="attr" />
+  </define>
+  <define name="Caption">
+    <element name="Caption">
+      <ref name="attlist_Caption" />
+      <optional>
+        <ref name="ShortCaption" />
+      </optional>
+      <zeroOrMore>
+        <ref name="block" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Caption" combine="interleave">
+    <empty />
+  </define>
+  <define name="ShortCaption">
+    <element name="ShortCaption">
+      <ref name="attlist_ShortCaption" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_ShortCaption" combine="interleave">
+    <empty />
+  </define>
+  <define name="colspecs">
+    <element name="colspecs">
+      <ref name="attlist_colspecs" />
+      <oneOrMore>
+        <ref name="ColSpec" />
+      </oneOrMore>
+    </element>
+  </define>
+  <define name="attlist_colspecs" combine="interleave">
+    <empty />
+  </define>
+  <define name="ColSpec">
+    <element name="ColSpec">
+      <ref name="attlist_ColSpec" />
+      <empty />
+    </element>
+  </define>
+  <define name="attlist_ColSpec" combine="interleave">
+    <optional>
+      <attribute name="alignment" a:defaultValue="AlignDefault">
+        <choice>
+          <value>AlignLeft</value>
+          <value>AlignRight</value>
+          <value>AlignCenter</value>
+          <value>AlignDefault</value>
+        </choice>
+      </attribute>
+    </optional>
+    <optional>
+      <attribute name="col-width" a:defaultValue="0">
+        <data type="double">
+          <param name="minInclusive">0</param>
+          <param name="maxInclusive">1</param>
+        </data>
+      </attribute>
+    </optional>
+  </define>
+  <define name="TableHead">
+    <element name="TableHead">
+      <ref name="attlist_TableHead" />
+      <zeroOrMore>
+        <ref name="Row" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_TableHead" combine="interleave">
+    <ref name="attr" />
+  </define>
+  <define name="TableFoot">
+    <element name="TableFoot">
+      <ref name="attlist_TableFoot" />
+      <zeroOrMore>
+        <ref name="Row" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_TableFoot" combine="interleave">
+    <ref name="attr" />
+  </define>
+  <define name="TableBody">
+    <element name="TableBody">
+      <ref name="attlist_TableBody" />
+      <ref name="header" />
+      <ref name="body" />
+    </element>
+  </define>
+  <define name="attlist_TableBody" combine="interleave">
+    <optional>
+      <attribute name="row-head-columns" a:defaultValue="0" />
+    </optional>
+    <ref name="attr" />
+  </define>
+  <define name="header">
+    <element name="header">
+      <ref name="attlist_header" />
+      <zeroOrMore>
+        <ref name="Row" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_header" combine="interleave">
+    <empty />
+  </define>
+  <define name="body">
+    <element name="body">
+      <ref name="attlist_body" />
+      <zeroOrMore>
+        <ref name="Row" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_body" combine="interleave">
+    <empty />
+  </define>
+  <define name="Row">
+    <element name="Row">
+      <ref name="attlist_Row" />
+      <zeroOrMore>
+        <ref name="Cell" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Row" combine="interleave">
+    <ref name="attr" />
+  </define>
+  <define name="Cell">
+    <element name="Cell">
+      <ref name="attlist_Cell" />
+      <zeroOrMore>
+        <ref name="block" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Cell" combine="interleave">
+    <optional>
+      <attribute name="alignment" a:defaultValue="AlignDefault">
+        <choice>
+          <value>AlignLeft</value>
+          <value>AlignRight</value>
+          <value>AlignCenter</value>
+          <value>AlignDefault</value>
+        </choice>
+      </attribute>
+    </optional>
+    <optional>
+      <attribute name="row-span" a:defaultValue="1">
+        <data type="positiveInteger" />
+      </attribute>
+    </optional>
+    <optional>
+      <attribute name="col-span" a:defaultValue="1">
+        <data type="positiveInteger" />
+      </attribute>
+    </optional>
+    <ref name="attr" />
+  </define>
+  <define name="Figure">
+    <element name="Figure">
+      <ref name="attlist_Figure" />
+      <ref name="Caption" />
+      <zeroOrMore>
+        <ref name="block" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Figure" combine="interleave">
+    <ref name="attr" />
+  </define>
+  <define name="LineBlock">
+    <element name="LineBlock">
+      <ref name="attlist_LineBlock" />
+      <oneOrMore>
+        <ref name="line" />
+      </oneOrMore>
+    </element>
+  </define>
+  <define name="attlist_LineBlock" combine="interleave">
+    <empty />
+  </define>
+  <define name="line">
+    <element name="line">
+      <ref name="attlist_line" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_line" combine="interleave">
+    <empty />
+  </define>
+  <define name="CodeBlock">
+    <element name="CodeBlock">
+      <ref name="attlist_CodeBlock" />
+      <text />
+    </element>
+  </define>
+  <define name="attlist_CodeBlock" combine="interleave">
+    <ref name="attr" />
+  </define>
+  <define name="RawBlock">
+    <element name="RawBlock">
+      <ref name="attlist_RawBlock" />
+      <text />
+    </element>
+  </define>
+  <define name="attlist_RawBlock" combine="interleave">
+    <attribute name="format" />
+  </define>
+  <define name="Space">
+    <element name="Space">
+      <ref name="attlist_Space" />
+      <empty />
+    </element>
+  </define>
+  <define name="attlist_Space" combine="interleave">
+    <optional>
+      <attribute name="count" a:defaultValue="1">
+        <data type="positiveInteger" />
+      </attribute>
+    </optional>
+  </define>
+  <define name="Str">
+    <element name="Str">
+      <ref name="attlist_Str" />
+      <empty />
+    </element>
+  </define>
+  <define name="attlist_Str" combine="interleave">
+    <optional>
+      <attribute name="content" a:defaultValue="" />
+    </optional>
+  </define>
+  <define name="Emph">
+    <element name="Emph">
+      <ref name="attlist_Emph" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Emph" combine="interleave">
+    <empty />
+  </define>
+  <define name="Strong">
+    <element name="Strong">
+      <ref name="attlist_Strong" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Strong" combine="interleave">
+    <empty />
+  </define>
+  <define name="Underline">
+    <element name="Underline">
+      <ref name="attlist_Underline" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Underline" combine="interleave">
+    <empty />
+  </define>
+  <define name="Strikeout">
+    <element name="Strikeout">
+      <ref name="attlist_Strikeout" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Strikeout" combine="interleave">
+    <empty />
+  </define>
+  <define name="Superscript">
+    <element name="Superscript">
+      <ref name="attlist_Superscript" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Superscript" combine="interleave">
+    <empty />
+  </define>
+  <define name="Subscript">
+    <element name="Subscript">
+      <ref name="attlist_Subscript" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Subscript" combine="interleave">
+    <empty />
+  </define>
+  <define name="SmallCaps">
+    <element name="SmallCaps">
+      <ref name="attlist_SmallCaps" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_SmallCaps" combine="interleave">
+    <empty />
+  </define>
+  <define name="Span">
+    <element name="Span">
+      <ref name="attlist_Span" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Span" combine="interleave">
+    <ref name="attr" />
+  </define>
+  <define name="Quoted">
+    <element name="Quoted">
+      <ref name="attlist_Quoted" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Quoted" combine="interleave">
+    <optional>
+      <attribute name="quote-type" a:defaultValue="DoubleQuote">
+        <choice>
+          <value>SingleQuote</value>
+          <value>DoubleQuote</value>
+        </choice>
+      </attribute>
+    </optional>
+  </define>
+  <define name="Math">
+    <element name="Math">
+      <ref name="attlist_Math" />
+      <text />
+    </element>
+  </define>
+  <define name="attlist_Math" combine="interleave">
+    <optional>
+      <attribute name="math-type" a:defaultValue="InlineMath">
+        <choice>
+          <value>DisplayMath</value>
+          <value>InlineMath</value>
+        </choice>
+      </attribute>
+    </optional>
+  </define>
+  <define name="RawInline">
+    <element name="RawInline">
+      <ref name="attlist_RawInline" />
+      <text />
+    </element>
+  </define>
+  <define name="attlist_RawInline" combine="interleave">
+    <attribute name="format" />
+  </define>
+  <define name="Cite">
+    <element name="Cite">
+      <ref name="attlist_Cite" />
+      <zeroOrMore>
+        <choice>
+          <text />
+          <ref name="citations" />
+          <ref name="inline_element" />
+        </choice>
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Cite" combine="interleave">
+    <empty />
+  </define>
+  <define name="citations">
+    <element name="citations">
+      <ref name="attlist_citations" />
+      <oneOrMore>
+        <ref name="Citation" />
+      </oneOrMore>
+    </element>
+  </define>
+  <define name="attlist_citations" combine="interleave">
+    <empty />
+  </define>
+  <define name="Citation">
+    <element name="Citation">
+      <ref name="attlist_Citation" />
+      <optional>
+        <ref name="prefix" />
+      </optional>
+      <optional>
+        <ref name="suffix" />
+      </optional>
+    </element>
+  </define>
+  <define name="prefix">
+    <element name="prefix">
+      <ref name="attlist_prefix" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_prefix" combine="interleave">
+    <empty />
+  </define>
+  <define name="suffix">
+    <element name="suffix">
+      <ref name="attlist_suffix" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_suffix" combine="interleave">
+    <empty />
+  </define>
+  <define name="attlist_Citation" combine="interleave">
+    <optional>
+      <attribute name="id" />
+    </optional>
+    <optional>
+      <attribute name="note-num" />
+    </optional>
+    <optional>
+      <attribute name="hash" a:defaultValue="0" />
+    </optional>
+    <optional>
+      <attribute name="mode" a:defaultValue="AuthorInText">
+        <choice>
+          <value>AuthorInText</value>
+          <value>SuppressAuthor</value>
+          <value>NormalCitation</value>
+        </choice>
+      </attribute>
+    </optional>
+  </define>
+  <define name="Code">
+    <element name="Code">
+      <ref name="attlist_Code" />
+      <text />
+    </element>
+  </define>
+  <define name="attlist_Code" combine="interleave">
+    <ref name="attr" />
+  </define>
+  <define name="Image">
+    <element name="Image">
+      <ref name="attlist_Image" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Image" combine="interleave">
+    <optional>
+      <attribute name="title"/>
+    </optional>
+    <optional>
+      <attribute name="src"/>
+    </optional>
+    <ref name="attr"/>
+  </define>
+  <define name="Link">
+    <element name="Link">
+      <ref name="attlist_Link" />
+      <zeroOrMore>
+        <ref name="inline" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Link" combine="interleave">
+    <optional>
+      <attribute name="title"/>
+    </optional>
+    <optional>
+      <attribute name="href"/>
+    </optional>
+    <ref name="attr"/>
+  </define>
+  <define name="SoftBreak">
+    <element name="SoftBreak">
+      <ref name="attlist_SoftBreak" />
+      <empty />
+    </element>
+  </define>
+  <define name="attlist_SoftBreak" combine="interleave">
+    <empty />
+  </define>
+  <define name="LineBreak">
+    <element name="LineBreak">
+      <ref name="attlist_LineBreak" />
+      <empty />
+    </element>
+  </define>
+  <define name="attlist_LineBreak" combine="interleave">
+    <empty />
+  </define>
+  <define name="Note">
+    <element name="Note">
+      <ref name="attlist_Note" />
+      <zeroOrMore>
+        <ref name="block" />
+      </zeroOrMore>
+    </element>
+  </define>
+  <define name="attlist_Note" combine="interleave">
+    <empty />
+  </define>
+  <start>
+    <choice>
+      <ref name="Pandoc" />
+    </choice>
+  </start>
+</grammar>
diff --git a/tools/pandoc-xml.xsd b/tools/pandoc-xml.xsd
new file mode 100644
index 000000000..01834f80f
--- /dev/null
+++ b/tools/pandoc-xml.xsd
@@ -0,0 +1,602 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+A XML Schema definition for Pandoc XML format.
+Copyright   : Copyright (C) 2025- Massimiliano Farinella
+License     : GNU GPL, version 2 or above
+Maintainer  : Massimiliano Farinella <[email protected]>
+
+This is a XML Schema schema for the XML representation of Pandoc AST.
+It's an equivalent of native and JSON formats, but modeled as XML.
+You can use this schema to validate Pandoc XML documents.
+It's translated from pandoc-xml.dtd with the "Trang" software by James Clark,
+and adjusted manually to add some constraints:
+- elements with Attr can have arbitrary attributes (this is not possible with a DTD)
+- Header's "level", OrderedList's "start" and Cell's "rowspan" and "colspan" attributes
+  must be a positive integer and are equal to 1 if not specified
+- column widths in ColSpec must be between 0 and 1 (inclusive, with 0=ColWidthDefault)
+- the "count" attribute in the "<Space>" element must be a positive integer,
+  equal to 1 if not specified
+- OrderedList's number style and delimiter, ColSpec's and Cell's alignment,
+  Quoted's QuoteType and Math's Mathtype
+  can only take the values specified in pandoc-types
+- TableBody's row-head-columns must be zero (default, when not specified) or a positive integer
+-->
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
+  <xs:element name="Pandoc">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element ref="meta"/>
+        <xs:element ref="blocks"/>
+      </xs:sequence>
+      <xs:attributeGroup ref="attlist_Pandoc"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Pandoc">
+    <xs:attribute name="api-version" use="required"/>
+  </xs:attributeGroup>
+  <xs:element name="block" abstract="true"/>
+  <xs:element name="inline_element" abstract="true"/>
+  <xs:group name="inline">
+    <xs:sequence>
+      <xs:element minOccurs="0" ref="inline_element"/>
+    </xs:sequence>
+  </xs:group>
+  <xs:attributeGroup name="attr">
+    <xs:attribute name="id" type="xs:ID"/>
+    <xs:attribute name="class"/>
+    <xs:anyAttribute processContents="skip"/>
+  </xs:attributeGroup>
+  <xs:element name="metavalue" abstract="true"/>
+  <xs:element name="meta">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="entry"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="MetaMap" substitutionGroup="metavalue">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="entry"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="entry">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="metavalue"/>
+      </xs:sequence>
+      <xs:attributeGroup ref="attlist_entry"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_entry">
+    <xs:attribute name="key" use="required"/>
+  </xs:attributeGroup>
+  <xs:element name="MetaList" substitutionGroup="metavalue">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="metavalue"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="MetaBool" substitutionGroup="metavalue">
+    <xs:complexType>
+      <xs:attributeGroup ref="attlist_MetaBool"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_MetaBool">
+    <xs:attribute name="value" use="required">
+      <xs:simpleType>
+        <xs:restriction base="xs:token">
+          <xs:enumeration value="true"/>
+          <xs:enumeration value="false"/>
+        </xs:restriction>
+      </xs:simpleType>
+    </xs:attribute>
+  </xs:attributeGroup>
+  <xs:element name="MetaString" substitutionGroup="metavalue" type="xs:string"/>
+  <xs:element name="MetaInlines" substitutionGroup="metavalue">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="MetaBlocks" substitutionGroup="metavalue">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="block"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="blocks">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="block"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="Para" substitutionGroup="block">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="Plain" substitutionGroup="block">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="Header" substitutionGroup="block">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+      <xs:attributeGroup ref="attlist_Header"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Header">
+    <xs:attribute name="level" default="1" type="xs:positiveInteger"/>
+    <xs:attributeGroup ref="attr"/>
+  </xs:attributeGroup>
+  <xs:element name="Div" substitutionGroup="block">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="block"/>
+      </xs:sequence>
+      <xs:attributeGroup ref="attlist_Div"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Div">
+    <xs:attributeGroup ref="attr"/>
+  </xs:attributeGroup>
+  <xs:element name="BlockQuote" substitutionGroup="block">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="block"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="HorizontalRule" substitutionGroup="block">
+    <xs:complexType/>
+  </xs:element>
+  <xs:element name="BulletList" substitutionGroup="block">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element maxOccurs="unbounded" ref="item"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="OrderedList" substitutionGroup="block">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element maxOccurs="unbounded" ref="item"/>
+      </xs:sequence>
+      <xs:attributeGroup ref="attlist_OrderedList"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_OrderedList">
+    <xs:attribute name="start" default="1" type="xs:positiveInteger"/>
+    <xs:attribute name="number-style" default="DefaultStyle">
+      <xs:simpleType>
+        <xs:restriction base="xs:token">
+          <xs:enumeration value="DefaultStyle"/>
+          <xs:enumeration value="Example"/>
+          <xs:enumeration value="Decimal"/>
+          <xs:enumeration value="LowerRoman"/>
+          <xs:enumeration value="UpperRoman"/>
+          <xs:enumeration value="LowerAlpha"/>
+          <xs:enumeration value="UpperAlpha"/>
+        </xs:restriction>
+      </xs:simpleType>
+    </xs:attribute>
+    <xs:attribute name="number-delim" default="DefaultDelim">
+      <xs:simpleType>
+        <xs:restriction base="xs:token">
+          <xs:enumeration value="DefaultDelim"/>
+          <xs:enumeration value="Period"/>
+          <xs:enumeration value="OneParen"/>
+          <xs:enumeration value="TwoParens"/>
+        </xs:restriction>
+      </xs:simpleType>
+    </xs:attribute>
+  </xs:attributeGroup>
+  <xs:element name="DefinitionList" substitutionGroup="block">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element maxOccurs="unbounded" ref="item"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="item">
+    <xs:complexType>
+      <xs:choice>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="block"/>
+        <xs:sequence>
+          <xs:element ref="term"/>
+          <xs:element maxOccurs="unbounded" ref="def"/>
+        </xs:sequence>
+      </xs:choice>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="term">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="def">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="block"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="Table" substitutionGroup="block">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element ref="Caption"/>
+        <xs:element ref="colspecs"/>
+        <xs:element ref="TableHead"/>
+        <xs:element maxOccurs="unbounded" ref="TableBody"/>
+        <xs:element ref="TableFoot"/>
+      </xs:sequence>
+      <xs:attributeGroup ref="attlist_Table"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Table">
+    <xs:attributeGroup ref="attr"/>
+  </xs:attributeGroup>
+  <xs:element name="Caption">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" ref="ShortCaption"/>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="block"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="ShortCaption">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="colspecs">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element maxOccurs="unbounded" ref="ColSpec"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="ColSpec">
+    <xs:complexType>
+      <xs:attributeGroup ref="attlist_ColSpec"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_ColSpec">
+    <xs:attribute name="alignment" default="AlignDefault">
+      <xs:simpleType>
+        <xs:restriction base="xs:token">
+          <xs:enumeration value="AlignLeft"/>
+          <xs:enumeration value="AlignRight"/>
+          <xs:enumeration value="AlignCenter"/>
+          <xs:enumeration value="AlignDefault"/>
+        </xs:restriction>
+      </xs:simpleType>
+    </xs:attribute>
+    <xs:attribute name="col-width" default="0">
+      <xs:simpleType>
+        <xs:restriction base="xs:double">
+          <xs:minInclusive value="0"/>
+          <xs:maxInclusive value="1"/>
+        </xs:restriction>
+      </xs:simpleType>
+    </xs:attribute>
+  </xs:attributeGroup>
+  <xs:element name="TableHead">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="Row"/>
+      </xs:sequence>
+      <xs:attributeGroup ref="attlist_TableHead"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_TableHead">
+    <xs:attributeGroup ref="attr"/>
+  </xs:attributeGroup>
+  <xs:element name="TableFoot">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="Row"/>
+      </xs:sequence>
+      <xs:attributeGroup ref="attlist_TableFoot"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_TableFoot">
+    <xs:attributeGroup ref="attr"/>
+  </xs:attributeGroup>
+  <xs:element name="TableBody">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element ref="header"/>
+        <xs:element ref="body"/>
+      </xs:sequence>
+      <xs:attributeGroup ref="attlist_TableBody"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_TableBody">
+    <xs:attribute name="row-head-columns" default="0"/>
+    <xs:attributeGroup ref="attr"/>
+  </xs:attributeGroup>
+  <xs:element name="header">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="Row"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="body">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="Row"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="Row">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="Cell"/>
+      </xs:sequence>
+      <xs:attributeGroup ref="attlist_Row"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Row">
+    <xs:attributeGroup ref="attr"/>
+  </xs:attributeGroup>
+  <xs:element name="Cell">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="block"/>
+      </xs:sequence>
+      <xs:attributeGroup ref="attlist_Cell"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Cell">
+    <xs:attribute name="alignment" default="AlignDefault">
+      <xs:simpleType>
+        <xs:restriction base="xs:token">
+          <xs:enumeration value="AlignLeft"/>
+          <xs:enumeration value="AlignRight"/>
+          <xs:enumeration value="AlignCenter"/>
+          <xs:enumeration value="AlignDefault"/>
+        </xs:restriction>
+      </xs:simpleType>
+    </xs:attribute>
+    <xs:attribute name="row-span" default="1" type="xs:positiveInteger"/>
+    <xs:attribute name="col-span" default="1" type="xs:positiveInteger"/>
+    <xs:attributeGroup ref="attr"/>
+  </xs:attributeGroup>
+  <xs:element name="Figure" substitutionGroup="block">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element ref="Caption"/>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="block"/>
+      </xs:sequence>
+      <xs:attributeGroup ref="attlist_Figure"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Figure">
+    <xs:attributeGroup ref="attr"/>
+  </xs:attributeGroup>
+  <xs:element name="LineBlock" substitutionGroup="block">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element maxOccurs="unbounded" ref="line"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="line">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="CodeBlock" substitutionGroup="block">
+    <xs:complexType mixed="true">
+      <xs:attributeGroup ref="attlist_CodeBlock"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_CodeBlock">
+    <xs:attributeGroup ref="attr"/>
+  </xs:attributeGroup>
+  <xs:element name="RawBlock" substitutionGroup="block">
+    <xs:complexType mixed="true">
+      <xs:attributeGroup ref="attlist_RawBlock"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_RawBlock">
+    <xs:attribute name="format" use="required"/>
+  </xs:attributeGroup>
+  <xs:element name="Space" substitutionGroup="inline_element">
+    <xs:complexType>
+      <xs:attributeGroup ref="attlist_Space"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Space">
+    <xs:attribute name="count" default="1" type="xs:positiveInteger"/>
+  </xs:attributeGroup>
+  <xs:element name="Str" substitutionGroup="inline_element">
+    <xs:complexType>
+      <xs:attributeGroup ref="attlist_Str"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Str">
+    <xs:attribute name="content" default=""/>
+  </xs:attributeGroup>
+  <xs:element name="Emph" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="Strong" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="Underline" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="Strikeout" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="Superscript" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="Subscript" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="SmallCaps" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="Span" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+      <xs:attributeGroup ref="attlist_Span"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Span">
+    <xs:attributeGroup ref="attr"/>
+  </xs:attributeGroup>
+  <xs:element name="Quoted" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+      <xs:attributeGroup ref="attlist_Quoted"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Quoted">
+    <xs:attribute name="quote-type" default="DoubleQuote">
+      <xs:simpleType>
+        <xs:restriction base="xs:token">
+          <xs:enumeration value="SingleQuote"/>
+          <xs:enumeration value="DoubleQuote"/>
+        </xs:restriction>
+      </xs:simpleType>
+    </xs:attribute>
+  </xs:attributeGroup>
+  <xs:element name="Math" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:attributeGroup ref="attlist_Math"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Math">
+    <xs:attribute name="math-type" default="InlineMath">
+      <xs:simpleType>
+        <xs:restriction base="xs:token">
+          <xs:enumeration value="DisplayMath"/>
+          <xs:enumeration value="InlineMath"/>
+        </xs:restriction>
+      </xs:simpleType>
+    </xs:attribute>
+  </xs:attributeGroup>
+  <xs:element name="RawInline" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:attributeGroup ref="attlist_RawInline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_RawInline">
+    <xs:attribute name="format" use="required"/>
+  </xs:attributeGroup>
+  <xs:element name="Cite" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:choice minOccurs="0" maxOccurs="unbounded">
+        <xs:element ref="citations"/>
+        <xs:element ref="inline_element"/>
+      </xs:choice>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="citations">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element maxOccurs="unbounded" ref="Citation"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="Citation">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" ref="prefix"/>
+        <xs:element minOccurs="0" ref="suffix"/>
+      </xs:sequence>
+      <xs:attributeGroup ref="attlist_Citation"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="prefix">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:element name="suffix">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Citation">
+    <xs:attribute name="id"/>
+    <xs:attribute name="note-num"/>
+    <xs:attribute name="hash" default="0"/>
+    <xs:attribute name="mode" default="AuthorInText">
+      <xs:simpleType>
+        <xs:restriction base="xs:token">
+          <xs:enumeration value="AuthorInText"/>
+          <xs:enumeration value="SuppressAuthor"/>
+          <xs:enumeration value="NormalCitation"/>
+        </xs:restriction>
+      </xs:simpleType>
+    </xs:attribute>
+  </xs:attributeGroup>
+  <xs:element name="Code" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:attributeGroup ref="attlist_Code"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Code">
+    <xs:attributeGroup ref="attr"/>
+  </xs:attributeGroup>
+  <xs:element name="Image" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+      <xs:attributeGroup ref="attlist_Image"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Image">
+    <xs:attribute name="title"/>
+    <xs:attribute name="src"/>
+    <xs:attributeGroup ref="attr"/>
+  </xs:attributeGroup>
+  <xs:element name="Link" substitutionGroup="inline_element">
+    <xs:complexType mixed="true">
+      <xs:group minOccurs="0" maxOccurs="unbounded" ref="inline"/>
+      <xs:attributeGroup ref="attlist_Link"/>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="attlist_Link">
+    <xs:attribute name="title"/>
+    <xs:attribute name="href"/>
+    <xs:attributeGroup ref="attr"/>
+  </xs:attributeGroup>
+  <xs:element name="SoftBreak" substitutionGroup="inline_element">
+    <xs:complexType/>
+  </xs:element>
+  <xs:element name="LineBreak" substitutionGroup="inline_element">
+    <xs:complexType/>
+  </xs:element>
+  <xs:element name="Note" substitutionGroup="inline_element">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element minOccurs="0" maxOccurs="unbounded" ref="block"/>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+</xs:schema>