A Complete Example (→ B.1)
  
  
                             Every element shows up
  
  
                                 Version 1.6.7
  
  
                                 February 2024
  
  
                                  Frank Lübeck
  
                                 Max Neunhöffer
  
  
  
            If the subtitle is not sufficient, this <TitleComment> element can
            be used for a slightly longer text on the front page.
  
  
  
  Frank Lübeck
      Email:    mailto:Frank.Luebeck@Math.RWTH-Aachen.De
  Max Neunhöffer
      Email:    mailto:neunhoef at mcs.st-and.ac.uk
  
  
  Address: Lehrstuhl für Algebra und Zahlentheorie
           Pontdriesch 14/16
           52062 Aachen
           (Germany)
  
  
  -------------------------------------------------------
  Abstract
  This  document  tries to use all elements that exist in GAPDoc. In addition,
  the  final  output not only contains the usual content, but also an appendix
  with  the  source  text.  There are also links from the usual content to the
  corresponding  source  text.  This  should  enable new users to learn GAPDoc
  quickly.
  
  
  -------------------------------------------------------
  Copyright
  © 2000-2024 by Frank Lübeck and Max Neunhöffer
  
  
  -------------------------------------------------------
  Acknowledgements
  We  thank  Lehrstuhl  für  Algebra und Zahlentheorie (former Lehrstuhl D für
  Mathematik).
  
  
  -------------------------------------------------------
  Colophon
  This is the Colophon page.
  
  
  -------------------------------------------------------
  
  
  Contents (GAPDoc Example)
  
  1 Sectioning Elements
    1.1 Normal subsections
      1.1-1 A subsection
      1.1-2 Another subsection
    1.2 ManSections
      1.2-1 f
      1.2-2 \^\{\}\[\]\<\&
      1.2-3 MyOperation
      1.2-4 MyOperation
      1.2-5 MyOperation
      1.2-6 MyConstructor
      1.2-7 IsBla
      1.2-8 IsBlubb
      1.2-9 NumberBlobbs
      1.2-10 AllBlibbs
      1.2-11 BlibbsFamily
      1.2-12 InfoBlibbs
  2 Other Markup
    2.1 Various types of text
    2.2 Formulae
    2.3 Crossreferencing
    2.4 Lists and Tables
    2.5 Entities and Special Characters
  A An Appendix
  B The Source
    B.1 TitlePage (Source)
    B.2 Before First Chapter (Source)
    B.3 First Chapter (Source)
    B.4 ManSections (Source)
    B.5 Various Types of Text (Source)
    B.6 Verbatim-like text (Source)
    B.7 Formulae (Source)
    B.8 Crossreferencing (Source)
    B.9 Lists and Tables (Source)
    B.10 Entities and Special Characters (Source)
    B.11 Appendix (Source)
  
  
  ────────────────────────────────────────────────────────────────────────────
  Text before chapter 1. (→ B.2)
  
  
  1 Sectioning Elements
  
  Text before the section 1.1. (→ B.2)
  
  
  1.1 Normal subsections
  
  [→ B.3]
  
  
  1.1-1 A subsection
  
  This is text in the first subsection.
  
  
  1.1-2 Another subsection
  
  This  is  text  in  the second subsection. This subsection has a label, such
  that one can reference it.
  
  
  1.2 ManSections
  
  [→ B.4]
  
  1.2-1 f
  
  ‣ f( x[, y] ) ───────────────────────────────────────────────────── function
  Returns:  an element in IsBlubb (1.2-8) or fail.
  
  This function calculates something.
  
  1.2-2 \^\{\}\[\]\<\&
  
  ‣ \^\{\}\[\]\<\&( c ) ─────────────────────────────────────────────── method
  
  This method is for an operation with a tricky name.
  
  1.2-3 MyOperation
  
  ‣ MyOperation( x ) ─────────────────────────────────────────────── operation
  
  The operation MyOperation operates on x.
  
  1.2-4 MyOperation
  
  ‣ MyOperation( x ) ────────────────────────────────────────────────── method
  
  This method calculates something by the generic method.
  
  1.2-5 MyOperation
  
  ‣ MyOperation( x[, good_hint] ) ───────────────────────────────────── method
  
  This  is  the super-fast method for the operation MyOperation (1.2-3) if the
  argument  x  is  in  the  representation  IsBla (1.2-7). It will become even
  faster if the optional argument good_hint is given.
  
  1.2-6 MyConstructor
  
  ‣ MyConstructor( filt, x ) ───────────────────────────────────── constructor
  
  The constructor MyConstructor constructs from x an object in filt.
  
  1.2-7 IsBla
  
  ‣ IsBla( obj ) ────────────────────────────────────────────── representation
  
  For  objects  in  this  representation  there  is  a  super-fast method (see
  MyOperation (1.2-5)) for the operation MyOperation (1.2-3).
  
  1.2-8 IsBlubb
  
  ‣ IsBlubb( obj ) ────────────────────────────────────────────────── property
  
  A property.
  
  1.2-9 NumberBlobbs
  
  ‣ NumberBlobbs( obj ) ──────────────────────────────────────────── attribute
  
  An attribute. Number of blobbs.
  
  1.2-10 AllBlibbs
  
  ‣ AllBlibbs ──────────────────────────────────────────────── global variable
  
  This global variable holds a list of all blibbs.
  
  1.2-11 BlibbsFamily
  
  ‣ BlibbsFamily ────────────────────────────────────────────────────── family
  
  Family of all blibbs.
  
  1.2-12 InfoBlibbs
  
  ‣ InfoBlibbs ──────────────────────────────────────────────────── info class
  
  This info class is used throughout the library of blibbs.
  
  
  2 Other Markup
  
  
  2.1 Various types of text
  
  [→ B.5]
  
  In  this  section we present examples for all the various types of text that
  are possible in GAPDoc:
  
   •    This is emphasized.
  
   •    Keywords are typeset like this and that.
  
   •    Arguments of functions have an element. They look like this: x and y.
  
   •    Code   can   be  written  with  the  Code  element:  if  x  =  y  then
        Print("Equal"); fi; or while true do Print("Hello"); od;.
  
   •    Filenames    have   their   own   element:   /usr/local/ca/gap4r2   or
        pkg/xgap/doc.
  
   •    Buttons, menus, menu entries, and such things are also supported: <OK>
        or <Cancel>.
  
   •    Packages are typeset like this: Small Groups Library
  
   •    Quoted text: "This is a text in quotes."
  
  Paragraphs are separated by the empty Par or P element.
  
  Alternatives  for different output formats: This is other than LaTeX output,
  namely: Text output.
  
  There are also three elements to typeset "verbatim-like" text. (→ B.6)
  
  The first is a Listing:
  
  ────────────────────────────────  GAP code  ────────────────────────────────
    Sieve := function(n)
      # Returns the primes less than n
      local l,p,i;
      l := [1..n]; Unbind(l[1]);
      p := 2;
      while p^2 <= n do
          if IsBound(l[p]) then
              i := 2 * p;
              while i <= n do Unbind(l[i]); i := i + p; od;
          fi;
          p := p + 1;
      od;
      return Compacted(l);
    end;
  ────────────────────────────────────────────────────────────────────────────
  
  Here is a Log of a GAP session using this function:
  
  ────────────────────────────────  Example  ─────────────────────────────────
    gap> Sieve(100);
    [ 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61,
      67, 71, 73, 79, 83, 89, 97 ]
    gap> Length(last);
    25
  ────────────────────────────────────────────────────────────────────────────
  
  Here is a GAP Example session that is automatically tested:
  
  ────────────────────────────────  Example  ─────────────────────────────────
    gap> s := Size(CharacterTable("M"));
    808017424794512875886459904961710757005754368000000000
    gap> s < 10^53;                     
    false
    gap> s < 10^54;
    true
  ────────────────────────────────────────────────────────────────────────────
  
  
  2.2 Formulae
  
  [→ B.7]
  
  There are three types of formulae.
  
  The  first  is  the normal math mode of LaTeX: $b_i \cdot b_j = \sum_{k=1}^d
  h_{ijk} b_k$. Then there are displayed formulae:
  
  
        \Longrightarrow   \quad   \left(\sum_{i=1}^d  x_i  b_i  \right)  \cdot
        \left(\sum_{j=1}^d  y_j  b_j  \right) = \sum_{k=1}^d \left( \sum_{i,j}
        x_i y_j h_{ijk} \right) b_k
  
  
  
  If  possible,  use the Alt element to specify a better readable text version
  of such a formula as in the following example:
  
           d                d                 d   
         -----            -----             -----  -----                 
          \                \                 \      \                    
   ==> (   )  x_i b_i )(    )  y_j b_j ) =    )  (   )  x_i y_j h_ijk ) b_k
          /                /                 /      /                    
         -----            -----             -----  -----                
         i = 1            j = 1             k = 1   i,j                
  
  For  small  formulae  without "difficult" parts use the M element: b_i, x^2,
  x^2  +  2x  +  1 = (x + 1)^2. Note that here whitespace matters for text (or
  HTML) output.
  
  Here  are  two  formulae  containing  less than characters which are special
  characters for XML: a < b < c < d and e < f.
  
  Using the Mode attribute of a Display element formulae like
  
  
        a ⟶ a mod m'
  
  can also be displayed nicely in text and HTML output.
  
  
  2.3 Crossreferencing
  
  [→ B.8]
  
  In this section we demonstrate various references to parts of this document.
  Here  is a reference to this section: 2.3. Here is a reference to chapter 1,
  to appendix A, and to subsection 1.1-1.
  
  We  distinguish  among  others  references  to functions (see f (1.2-1)), to
  methods  with  tricky  name (see \^\{\}\[\]\<\& (1.2-2)), to operations (see
  MyOperation  (1.2-3)),  to  methods  (see MyOperation (1.2-4) or MyOperation
  (1.2-5)),  to  filters  (see  IsBla  (1.2-7)),  to  properties  (see IsBlubb
  (1.2-8)),  to attributes (see NumberBlobbs (1.2-9)), to variables (AllBlibbs
  (1.2-10)), to families (see BlibbsFamily (1.2-11)), and to info classes (see
  InfoBlibbs (1.2-12)).
  
  There  are  also references to labels: see 2.3, to other books: see 'GAPDoc:
  What  is  a DTD?' or IsSubgroup (Reference: IsSubgroup) in the GAP reference
  manual.
  
  References to sections come in two styles: 1 or 'Sectioning Elements'.
  
  Another  type  of  cross  referencing  is  bibliography. Here is a citation:
  [CR81, (5.22)] is an interesting lemma.
  
  There are also URLs:
  
  https://www.math.rwth-aachen.de/
  
  Email         addresses         have        a        special        element:
  mailto:Frank.Luebeck@Math.RWTH-Aachen.De
  
  and Homepages another one: https://www.math.rwth-aachen.de/~Frank.Luebeck/
  
  And      here      is      a      link      to     the     EDIM     archives
  (https://www.math.rwth-aachen.de/~Frank.Luebeck/gap/EDIM/index.html#ARCHS).
  
  One   can   generate   index   entries   as   follows  (look  up  the  words
  "TeX-UserGroup",  "RWTH",  "Aachen,  Hauptbahnhof",  and  "GAPDoc,  for  GAP
  programmers").
  
  
  2.4 Lists and Tables
  
  [→ B.9]
  
  There are
  
   •    lists
  
   •    enumerations, and
  
   •    tables
  
  or:
  
   1.   lists
  
   2.   enumerations, and
  
   3.   tables
  
  or with marks:
  
  lists:
        not numbered
  
  enumerations:
        numbered
  
  tables:
        two-dimensional
  
  Lists can also be nested:
  
   1.    1.   first item of inner enumeration
  
         2.   second item of inner enumeration
  
   2.    •    first item of inner list
  
         •    second item of inner list
  
  Here is a table:
  
      ┌────────┬───────┬───────────┐
      │ Object │ Price │ available │ 
      ├────────┼───────┼───────────┤
      ├────────┼───────┼───────────┤
      │   Shoe │ $1,00 │ there     │ 
      ├────────┼───────┼───────────┤
      │    Hat │ $2,00 │ not there │ 
      └────────┴───────┴───────────┘
  
       Table: Prices
  
  
  
  2.5 Entities and Special Characters
  
  [→ B.10]
  
  Here is a table of special characters, the first two are special for XML and
  must  be  typed in by entities in GAPDoc documents. The other characters are
  special for LaTeX but in GAPDoc they can be typed directly.
  
      ┌───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┐
      │ & │ < │ > │ # │ $ │ % │ ~ │ \ │ { │ } │ _ │ ^ │   │ 
      └───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┘
  
       Table: Special characters in character data
  
  
  And here are the predefined entities in GAPDoc:
  
      ┌─────────────┬─────────┐
      │ &GAP;       │ GAP     │ 
      ├─────────────┼─────────┤
      │ &GAPDoc;    │ GAPDoc  │ 
      ├─────────────┼─────────┤
      │ &TeX;       │ TeX     │ 
      ├─────────────┼─────────┤
      │ &LaTeX;     │ LaTeX   │ 
      ├─────────────┼─────────┤
      │ &BibTeX;    │ BibTeX  │ 
      ├─────────────┼─────────┤
      │ &MeatAxe;   │ MeatAxe │ 
      ├─────────────┼─────────┤
      │ &XGAP;      │ XGAP    │ 
      ├─────────────┼─────────┤
      │ &copyright; │ ©       │ 
      └─────────────┴─────────┘
  
       Table: Predefined Entities in the GAPDoc system
  
  
  And some more for mathematical symbols: ℂ, ℤ, ℕ, ℙ, ℚ, ℍ, ℝ.
  
  
  A An Appendix
  
  [→ B.11]
  
  This is an appendix.
  
  
  B The Source
  
  
  B.1 TitlePage (Source)
  
  ────────────────────────────────────────────────────────────────────────────
    <TitlePage>
      <Title>A Complete Example (&see; <Ref Sect="One"/>)</Title>
      <Subtitle>Every element shows up</Subtitle>
      <Version>Version 1.6.7
    </Version>
      <TitleComment>
      If the subtitle ist not sufficient, this &lt;TitleComment> 
      element can be used for a slightly longer text on the front page.
      </TitleComment>
      <Author>Frank Lübeck 
              <Email>Frank.Luebeck@Math.RWTH-Aachen.De</Email> 
      </Author>
      <Author> Max Neunhöffer 
              <Email>neunhoef at mcs.st-and.ac.uk</Email>
      </Author>
      <Date>January 2022</Date>
      <Address>
      Lehrstuhl für Algebra und Zahlentheorie<Br/>Pontdriesch 
      14/16<Br/> 52062 Aachen<Br/> (Germany)
      </Address>
      <Abstract>This document tries to use all elements that exist in &GAPDoc;.
                In addition, the final output not only contains the usual
                content, but also an appendix with the source text. There
                are also links from the usual content to the corresponding
                source text. This should enable new users to learn &GAPDoc;
                quickly.
      </Abstract>
      <Copyright>&copyright; 2000-2022 by Frank Lübeck and Max Neunhöffer
      </Copyright>
      <Acknowledgements>We thank Lehrstuhl für Algebra und Zahlentheorie 
      (former Lehrstuhl D für Mathematik).
      </Acknowledgements>
      <Colophon>This is the Colophon page.
      </Colophon>
    </TitlePage>
  ────────────────────────────────────────────────────────────────────────────
  
  
  B.2 Before First Chapter (Source)
  
  ────────────────────────────────────────────────────────────────────────────
    <TableOfContents/>
    
    <Body>
    
      Text before chapter <Ref Chap="First"/>.
    
    <Chapter Label="First"><Heading>Sectioning Elements</Heading>
    
      Text before the section <Ref Sect="FirstSect"/>.
  ────────────────────────────────────────────────────────────────────────────
  
  
  B.3 First Chapter (Source)
  
  [1.0]
  
  ────────────────────────────────────────────────────────────────────────────
    <Section Label="FirstSect"><Heading>Normal subsections</Heading>
    
      <Subsection Label="Asub"><Heading>A subsection</Heading>
    
       This is text in the first subsection.
    
      </Subsection>
    
      <Subsection Label="Another"><Heading>Another subsection</Heading>
       
       This is text in the second subsection. This subsection 
       has a label, such that one can reference it.
    
      </Subsection>
    
     </Section>
  ────────────────────────────────────────────────────────────────────────────
  
  
  B.4 ManSections (Source)
  
  [1.2]
  
  ────────────────────────────────────────────────────────────────────────────
    <Section><Heading>ManSections</Heading>
    
      <ManSection>
       <Func Name="f" Arg="x[,y]" Comm="calculates something"/>
       <Returns>an element in <Ref Filt="IsBlubb" /> or <K>fail</K>.</Returns>
       <Description>
        This function calculates something.
       </Description>
      </ManSection>
    
      <ManSection>
       <Meth Name="\^\{\}\[\]\&lt;\&amp;" Arg="c" 
             Label="for nothing" Comm="tricky name"/>
       <Description>
        This method is for an operation with a tricky name.
       </Description>
      </ManSection>
    
      <ManSection>
       <Oper Name="MyOperation" Arg="x" Comm="calculates something"/>
       <Description>
        The operation <Ref Oper="MyOperation"/> operates on <Arg>x</Arg>.
       </Description>
      </ManSection>
       
      <ManSection>
       <Meth Name="MyOperation" Label="First" Arg="x" 
             Comm="generic method"/>
       <Description>
        This method calculates something by the generic method.
       </Description>
      </ManSection>
    
      <ManSection>
       <Meth Name="MyOperation" Label="for bla" Arg="x[, good_hint]"
             Comm="for bla arguments"/>
       <Description>
        This is the super-fast method for the operation
        <Ref Oper="MyOperation"/> if the argument <A>x</A> is in the
        representation <Ref Filt="IsBla"/>. It will become even faster if
        the optional argument <A>good_hint</A> is given.
       </Description>
      </ManSection>
    
      <ManSection>
       <Constr Name="MyConstructor" Arg="filt, x" Comm="constructs something"/>
       <Description>
        The constructor <Ref Oper="MyConstructor"/> constructs from <Arg>x</Arg>
        an object in <A>filt</A>.
       </Description>
      </ManSection>
    
      <ManSection>
       <Filt Name="IsBla" Arg="obj" Comm="representation bla"
             Type="representation"/>
       <Description>
        For objects in this representation there is a super-fast method
        (see <Ref Meth="MyOperation" Label="for bla"/>) for the operation
        <Ref Oper="MyOperation"/>.
       </Description>
      </ManSection>
    
      <ManSection>
       <Prop Name="IsBlubb" Arg="obj" Comm="property, whether object is blubb"/>
       <Description>
        A property.
       </Description>
      </ManSection>
    
      <ManSection>
       <Attr Name="NumberBlobbs" Arg="obj" Comm="number of blobbs"/>
       <Description>
        An attribute. Number of blobbs.
       </Description>
      </ManSection>
    
      <ManSection>
       <Var Name="AllBlibbs" Comm="list of all blibbs in the system"/>
       <Description>
        This global variable holds a list of all blibbs.
       </Description>
      </ManSection>
    
      <ManSection>
       <Fam Name="BlibbsFamily" Comm="family of blibbs"/>
       <Description>
        Family of all blibbs.
       </Description>
      </ManSection>
    
      <ManSection>
       <InfoClass Name="InfoBlibbs" Comm="InfoClass for the library of blibbs"/>
       <Description>
        This info class is used throughout the library of blibbs.
       </Description>
      </ManSection>
        
     </Section>
  ────────────────────────────────────────────────────────────────────────────
  
  
  B.5 Various Types of Text (Source)
  
  [2.0]
  
  ────────────────────────────────────────────────────────────────────────────
    <Chapter><Heading>Other Markup</Heading>
    
    <Section><Heading>Various types of text</Heading>
    
    In this section we present examples for all the various types of text
    that are possible in &GAPDoc;: 
    <List>
     <Item>
      <Emph>This</Emph> is <E>emphasized</E>.</Item>
     <Item>
      <E>Keywords</E> are typeset like <Keyword>this</Keyword> and <K>that</K>.
      </Item>
     <Item>
      <E>Arguments</E> of functions have an element. They look like this: 
        <Arg>x</Arg> and <A>y</A>.</Item>
     <Item> 
      <E>Code</E> can be written with the Code element: 
        <Code>if x = y then Print("Equal"); fi;</Code> or
        <C>while true do Print("Hello"); od;</C>.</Item> 
     <Item>
      <E>Filenames</E> have their own element:
        <File>/usr/local/ca/gap4r2</File> or <F>pkg/xgap/doc</F>.</Item>
     <Item>
      <E>Buttons</E>, <E>menus</E>, <E>menu entries</E>, and such things
        are also supported: <B>OK</B> or <Button>Cancel</Button>.</Item>
     <Item>
      <E>Packages</E> are typeset like this: 
        <Package>Small Groups Library</Package>
     </Item>
     <Item>
      <E>Quoted</E> text: <Q>This is a text in quotes.</Q>
     </Item>
    </List>
    
    <E>Paragraphs</E> are separated by the empty <C>Par</C> or <C>P</C> element.
    <Par/><E>Alternatives</E> for different output formats:
    
    <Alt Only="LaTeX">This is &LaTeX; output.</Alt>
    <Alt Not="LaTeX">This is other than &LaTeX; output, namely:
    <Alt Only="HTML"><![CDATA[<b>HTML</b>]]></Alt>
    <Alt Only="Text">Text</Alt> output.</Alt>
    
    <P/>
  ────────────────────────────────────────────────────────────────────────────
  
  
  B.6 Verbatim-like text (Source)
  
  [2.1]
  
  ────────────────────────────────────────────────────────────────────────────
    There are also three elements to typeset <Q>verbatim-like</Q> text.
    <P/>
    The first is a <E>Listing</E>:
    
    <Listing Type="GAP code">
    <![CDATA[Sieve := function(n)
      # Returns the primes less than n
      local l,p,i;
      l := [1..n]; Unbind(l[1]);
      p := 2;
      while p^2 <= n do
          if IsBound(l[p]) then
              i := 2 * p;
              while i <= n do Unbind(l[i]); i := i + p; od;
          fi;
          p := p + 1;
      od;
      return Compacted(l);
    end;]]>
    </Listing>
    
    Here is a <E>Log</E> of a &GAP; session using this function:
    
    <Log>
    gap&gt; Sieve(100);
    [ 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61,
      67, 71, 73, 79, 83, 89, 97 ]
    gap&gt; Length(last);
    25
    </Log>
    
    Here is a &GAP; <E>Example</E> session that is automatically tested:
    
    <Example>
    gap&gt; s := Size(CharacterTable("M"));
    808017424794512875886459904961710757005754368000000000
    gap&gt; s &lt; 10^53;                     
    false
    gap&gt; s &lt; 10^54;
    true
    </Example>
    
    </Section>
  ────────────────────────────────────────────────────────────────────────────
  
  
  B.7 Formulae (Source)
  
  [2.2]
  
  ────────────────────────────────────────────────────────────────────────────
    <Section><Heading>Formulae</Heading>
    
    There are three types of formulae. <P/>
    The first is the <E>normal math mode</E> of &LaTeX;: 
    
    <Math>b_i \cdot b_j = \sum_{k=1}^d h_{ijk} b_k</Math>. 
    
    Then there are <E>displayed formulae</E>:
    <Display>
       \Longrightarrow \quad \left(\sum_{i=1}^d x_i b_i \right) \cdot
       \left(\sum_{j=1}^d y_j b_j \right) =
       \sum_{k=1}^d \left( \sum_{i,j} x_i y_j h_{ijk} \right) b_k 
    </Display>
    
    If possible,  use the <C>Alt</C> element  to specify a better  readable text
    version of such a formula as in the following example:<P/>
    
    <Alt Not="Text,HTML"><Display>
       \Longrightarrow \quad \left(\sum_{i=1}^d x_i b_i \right) \cdot
       \left(\sum_{j=1}^d y_j b_j \right) =
       \sum_{k=1}^d \left( \sum_{i,j} x_i y_j h_{ijk} \right) b_k 
    </Display></Alt>
    <Alt Only="Text,HTML"><Verb>
             d                d                 d   
           -----            -----             -----  -----                 
            \                \                 \      \                    
     ==> (   )  x_i b_i )(    )  y_i b_i ) =    )  (   )  x_i y_j h_ijk ) b_k
            /                /                 /      /                    
           -----            -----             -----  -----                
           i = 1            i = 1             k = 1   i,j                
    </Verb><P/></Alt>
    
    For small formulae without <Q>difficult</Q> parts use the <C>M</C>
    element: <M>b_i</M>,
    <M>x^2</M>, <M>x^2 + 2x + 1 = (x + 1)^2</M>. Note that here whitespace 
    matters for text (or HTML) output).<P/>
    
    Here are two formulae containing less than characters which are special
    characters for XML:
    <M><![CDATA[a < b < c < d]]></M> and  <M>e &lt; f</M>.
    </Section>
  ────────────────────────────────────────────────────────────────────────────
  
  
  B.8 Crossreferencing (Source)
  
  [2.3]
  
  ────────────────────────────────────────────────────────────────────────────
    <Section Label="Cross"><Heading>Crossreferencing</Heading>
    
    <Label Name="there"/>
    
    In this section we demonstrate various references to parts of this
    document. Here is a reference to this section: <Ref Sect="Cross"/>.
    Here is a reference to chapter <Ref Chap="First"/>, to appendix
    <Ref Appendix="Appendix"/>, and to subsection <Ref Subsect="Asub"/>. 
    <P/>
    
    We distinguish among others references 
     to functions (see <Ref Func="f"/>), 
     to methods with tricky name (see 
                     <Ref Meth="\^\{\}\[\]\&lt;\&amp;" Label="for nothing"/>),
     to operations (see <Ref Oper="MyOperation"/>), 
     to methods (see <Ref Meth="MyOperation" Label="First"/> or 
                     <Ref Meth="MyOperation" Label="for bla"/>), 
     to filters (see <Ref Filt="IsBla"/>), 
     to properties (see <Ref Prop="IsBlubb"/>),
     to attributes (see <Ref Attr="NumberBlobbs"/>), 
     to variables (<Ref Var="AllBlibbs"/>), 
     to families (see <Ref Fam="BlibbsFamily"/>),
     and to info classes (see <Ref InfoClass="InfoBlibbs"/>).
    <P/>
    
    There are also references to labels: see <Ref Text="here" Label="there"/>,
    to other books: see <Ref Sect="syntaxXML" BookName="gapdoc"/> or
    <Ref Oper="IsSubgroup" BookName="ref"/> in the &GAP; reference
    manual.
    <P/>
    
    References to sections come in two styles: 
    <Ref Chap="First" Style="Number"/>
    or <Ref Chap="First" Style="Text"/>.
    <P/>
    
    Another type of cross referencing is bibliography. Here is a 
    citation: <Cite Key="CR1" Where="(5.22)"/> is an interesting lemma.
    <P/>
    
    There are also URLs:<P/>
    
    <URL>https://www.math.rwth-aachen.de/LDfM/</URL><P/>
    
    Email addresses have a special element:
    <Email>Frank.Luebeck@Math.RWTH-Aachen.De</Email>
    <P/>
    
    and Homepages another one:
    <Homepage>https://www.math.rwth-aachen.de/~Frank.Luebeck/</Homepage>
    <P/>
    
    One can generate index entries as follows (look up the words 
    <Q>&TeX;-UserGroup</Q>, <Q>RWTH</Q>, and <Q>Aachen, Hauptbahnhof</Q>).
    <Index Key="TeX-Usergroup">&TeX;-UserGroup</Index>
    <Index>RWTH</Index>
    <Index>Aachen <Subkey>Hauptbahnhof</Subkey></Index>
    <Index Key="GAPDoc" Subkey="for GAP programmers">&GAPDoc; 
    <Subkey>for &GAP; programmers</Subkey></Index>
    
    </Section>
  ────────────────────────────────────────────────────────────────────────────
  
  
  B.9 Lists and Tables (Source)
  
  [2.4]
  
  ────────────────────────────────────────────────────────────────────────────
    <Section><Heading>Lists and Tables</Heading>
    
    There are
    <List>
     <Item>lists</Item>
     <Item>enumerations, and</Item>
     <Item>tables</Item>
    </List>
    or:
    <Enum>
     <Item>lists</Item>
     <Item>enumerations, and</Item>
     <Item>tables</Item>
    </Enum>
    or with marks:
    <List>
     <Mark>lists:</Mark><Item> not numbered</Item>
     <Mark>enumerations:</Mark><Item> numbered</Item>
     <Mark>tables:</Mark><Item> two-dimensional</Item>
    </List>
    
    Lists can also be nested:
    <Enum>
     <Item>
       <Enum>
         <Item>first item of inner enumeration </Item>
         <Item>second item of inner enumeration </Item>
       </Enum>
     </Item>
     <Item>
       <List>
         <Item>first item of inner list </Item>
         <Item>second item of inner list </Item>
       </List>
      </Item>
    </Enum>
    
    Here is a <E>table</E>:
    
    <Table Align="|r|c|l|">
     <Caption>Prices</Caption>
     <HorLine/>
      <Row>
       <Item>Object</Item><Item>Price</Item><Item>available</Item>
      </Row>
     <HorLine/>
     <HorLine/>
      <Row>
       <Item>Shoe</Item><Item>$1,00</Item><Item>there</Item>
      </Row>
     <HorLine/>
      <Row>
       <Item>Hat</Item><Item>$2,00</Item><Item>not there</Item>
      </Row>
     <HorLine/>
    </Table>
    
    </Section>
  ────────────────────────────────────────────────────────────────────────────
  
  
  B.10 Entities and Special Characters (Source)
  
  [2.5]
  
  ────────────────────────────────────────────────────────────────────────────
    <Section><Heading>Entities and Special Characters</Heading>
    <Label Name="TenBack"/>
    
    [&see; <Ref Sect="Ten"/>]<P/>
    
    Here is a table of special characters, the first two are special for
    XML and must be typed in by entities in &GAPDoc; documents. The other 
    characters are special for &LaTeX; but in &GAPDoc; they can be typed
    directly. 
    
    <Table Align="|c|c|c|c|c|c|c|c|c|c|c|c|c|" Label="charsInCDATA"> 
     <Caption>Special characters in character data</Caption>
     <HorLine/> <Row> 
      <Item><C>&amp;</C></Item>
      <Item><C>&lt;</C></Item>
      <Item><C>></C></Item>
      <Item><C>#</C></Item>
      <Item><C>$</C></Item>
      <Item><C>%</C></Item>
      <Item><C>~</C></Item>
      <Item><C>\</C></Item>   
      <Item><C>{</C></Item>
      <Item><C>}</C></Item>
      <Item><C>_</C></Item>
      <Item><C>^</C></Item>
      <Item><C>&nbsp;</C></Item>
     </Row> <HorLine/>
    </Table>
    
    And here are the predefined entities in &GAPDoc;:
    
    <Table Align="|l|l|">
    <Caption>Predefined Entities in the &GAPDoc; system</Caption>
    <HorLine/>
    <Row> <Item><C>&amp;GAP;</C></Item>       <Item>&GAP;</Item> </Row>
    <HorLine/>
    <Row> <Item><C>&amp;GAPDoc;</C></Item>    <Item>&GAPDoc;</Item> </Row>
    <HorLine/>
    <Row> <Item><C>&amp;TeX;</C></Item>       <Item>&TeX;</Item> </Row>
    <HorLine/>
    <Row> <Item><C>&amp;LaTeX;</C></Item>     <Item>&LaTeX;</Item> </Row>
    <HorLine/>
    <Row> <Item><C>&amp;BibTeX;</C></Item>    <Item>&BibTeX;</Item> </Row>
    <HorLine/>
    <Row> <Item><C>&amp;MeatAxe;</C></Item>   <Item>&MeatAxe;</Item> </Row>
    <HorLine/>
    <Row> <Item><C>&amp;XGAP;</C></Item>      <Item>&XGAP;</Item> </Row>
    <HorLine/>
    <Row> <Item><C>&amp;copyright;</C></Item> <Item>&copyright;</Item> </Row>
    <HorLine/>
    </Table>
    
    And some more for mathematical symbols: 
    &CC;, &ZZ;, &NN;, &PP;, &QQ;, &HH;, &RR;.
    
    </Section>
    
    </Chapter>
    
    </Body>
  ────────────────────────────────────────────────────────────────────────────
  
  
  B.11 Appendix (Source)
  
  [A.0]
  
  ─────────────────────────────  GAPDoc source  ──────────────────────────────
    <Appendix><Heading>An Appendix</Heading>
    
    This is an appendix.
    </Appendix>
  ────────────────────────────────────────────────────────────────────────────
  
  
  
  References
  
  [CR81]  Curtis, C. W. and Reiner, I., Methods of Representation Theory, John
  Wiley & Sons, I, New York, Chichester, Brisbane, Toronto, Singapore (1981).
  
  
  
  ────────────────────────────────────────────────────────────────────────────
  
  
  Index
  
  \^\{\}\[\]\<\&, for nothing 1.2-2 
  Aachen, Hauptbahnhof 2.3 
  AllBlibbs 1.2-10 
  BlibbsFamily 1.2-11 
  f 1.2-1 
  GAPDoc, for GAP programmers 2.3 
  InfoBlibbs 1.2-12 
  IsBla 1.2-7 
  IsBlubb 1.2-8 
  MyConstructor 1.2-6 
  MyOperation 1.2-3 
      First 1.2-4 
      for bla 1.2-5 
  NumberBlobbs 1.2-9 
  RWTH 2.3 
  TeX-UserGroup 2.3 
  
  
  -------------------------------------------------------