\letter {}
  2d-mapping, 11
  2d-object, 4
\letter A
  `AbelianModuleAction', 25
  `AbelianModuleGroup', 25
  `AbelianModuleObject', 25
  Abelian Modules, \indexit{25}
  Actor of a Crossed Module, \indexit{19}
  `ActorXMod', 19
  `AllDerivations', 16
  `AllInducedXMods', 23
  `AllSections', 16
  `AutoGroup', of (pre-)crossed module, 5
    \sub of endomorphism class, 24
  `AutomorphismPermGroup', 19
\letter B
  `Boundary', of (pre-)cat1-group, 7
    \sub of (pre-)crossed module, 5
\letter C
  `Cat1', 8
  cat1-group, 7
  cat1-group morphism, 12
  Cat1-groups and pre-cat1-groups, \indexit{7}
  cat1-group selection, 9
  `Cat1ByPeifferQuotient', 8
  `Cat1Morphism', 12
  `Cat1MorphismByHoms', 12
  `Cat1OfXMod', 9
  `Centre', 19
  `CommonRepresentatives', 26
  `CommonTransversal', 26
  `CompositeDerivation', 17
  `CompositionMorphism', 13
  crossed module, 4
  crossed module morphism, 11
  Crossed modules, \indexit{4}
\letter D
  derivation, 15
  `DerivationByImages', 15
  `DerivationBySection', 16
  `DirectProduct', 6
  Distinct and Common Representatives, \indexit{26}
  `DistinctRepresentatives', 26
\letter E
  `EndoClassConjugators', 24
  `EndoClassIsomorphism', 24
  `EndoClassNaturalHom', 24
  `EndomorphismClasses', 24
  Endomorphism Classes and Automorphisms, \indexit{24}
\letter G
  `GeneratorImages', 15
\letter H
  `Head', 7
\letter I
  `IdentityMapping', of pre-cat1-groups, 12
    \sub of pre-crossed modules, 11
  `IdentitySubXMod', 6
  `ImagePositions', 17
  `ImagesList', 16
  `ImagesTable', 16
  Inclusion and Restriction Mappings, \indexit{24}
  `InclusionMappingGroups', 24
  `InclusionMorphism2dObjects', of pre-cat1-groups, 12
    \sub of pre-crossed modules, 11
  `InducedCat1', 21
  Induced crossed modules, \indexit{21}
  `InducedXMod', 21
  `InfoXMod', 3
  `InnerActor', 19
  `InnerAutomorphismCat1', of pre-cat1-groups, 12
  `InnerAutomorphismsByNormalSubgroup', 25
  `InnerAutomorphismXMod', 11
  `InnerMorphism', 19
  Introduction, \indexit{4}
  `IsAbelianModule', 25
  `IsAutomorphism2dObject', 11
  `IsBijective', 11
  `IsCat1Morphism', 11
  `IsCommonTransversal', 26
  `IsDerivation', 15
  `IsEndomorphism2dObject', 11
  `IsGroupOfAutomorphisms', 25
  `IsInducedCat1', 21
  `IsInducedXMod', 21
  `IsInjective', 11
  `IsomorphismPermObject', of pre-cat1-groups, 12
    \sub of pre-crossed modules, 11
  `IsPcPreXMod', 7
  `IsPermXMod', 7
  `IsPreCat1Morphism', 11
  `IsPreXModMorphism', 11
  `IsSection', 15
  `IsSingleValued', 11
  `IsSurjective', 11
  `IsTotal', 11
  `IsUp2dMapping', 15
  `IsXModMorphism', 11
\letter K
  `Kernel', 14
  `Kernel2dMapping', 14
  `KernelEmbedding', 7
\letter L
  `LueXMod', 19
\letter M
  `MappingToOne', 24
  `MorphismOfInducedXMod', 21
  Morphisms of pre-cat1-groups, \indexit{12}
  Morphisms of pre-crossed modules, \indexit{11}
\letter N
  `Name', of (pre-)cat1-group, 7
    \sub of (pre-)crossed module, 5
  `NormalSubXMods', 6
  `NorrieXMod', 19
\letter O
  `Object2d', 15
  Operations on morphisms, \indexit{13}
  `Order', 13
\letter P
  `PeifferSubgroup', 6
  pre-cat1-group, 7
  Pre-crossed modules, \indexit{6}
  `PreCat1ByEndomorphisms', 8
  `PreCat1ByNormalSubgroup', 8
  `PreCat1ByTailHeadEmbedding', 8
  `PreCat1Morphism', 12
  `PreCat1MorphismByHoms', 12
  `PreCat1OfPreXMod', 9
  `PreXModByBoundaryAndAction', 6
  `PreXModByCentralExtension', 6
  `PreXModMorphism', 11
  `PreXModMorphismByHoms', 11
  `PreXModOfPreCat1', 9
\letter R
  `Range', of (pre-)cat1-group, 7
    \sub of (pre-)crossed module, 5
    \sub of 2d-mapping, 11
  `RangeEmbedding', 7
  `RangeHom', 11
  `RegularDerivations', 16
  `RegularSections', 16
  `RestrictionMappingGroups', 24
  `Reverse', 8
\letter S
  section, 15
    \sub of cat1-group, 15
  `SectionByDerivation', 16
  `SectionByImages', 16
  Selection of a small cat1-group, \indexit{9}
  `Size', of (pre-)cat1-group, 7
    \sub of (pre-)crossed module, 5
  `SmallerDegreePerm2dObject', 12
  `Source', of (pre-)cat1-group, 7
    \sub of (pre-)crossed module, 5
    \sub of 2d-mapping, 11
  `SourceHom', 11
  `SubPreXMod', 6
  `SubXMod', 6
\letter T
  `Tail', 7
\letter U
  up2dmapping, of 2dobject, 15
\letter V
  Version 2.006, \indexit{28}
  Versions 2.002 -- 2.005, \indexit{28}
\letter W
  What needs doing next?, \indexit{28}
  Whitehead Groups and Monoids, \indexit{16}
  `WhiteheadGroupTable', 18
  `WhiteheadMonoidTable', 18
  Whitehead Multiplication, \indexit{15}
  `WhiteheadPermGroup', 18
  `WhiteheadTransMonoid', 18
  `WhiteheadXMod', 19
\letter X
  `XMod', 5
  `XModAction', 5
  `XModByAbelianModule', 5
  `XModByAutomorphismGroup', 5
  `XModByBoundaryAndAction', 5
  `XModByCentralExtension', 5
  `XModByGroupOfAutomorphisms', 5
  `XModByInnerAutomorphismGroup', 5
  `XModByNormalSubgroup', 5
  `XModByPeifferQuotient', 6
  `XModByTrivialAction', 5
  `XModMorphism', 11
  `XModMorphismByHoms', 11
  `XModOfCat1', 9
