Changes to sentence case refs #2223 and eliminates non-current comment

doc/Language/variables.pod6

@@ -75,7 +75,7 @@ The container type can be set with C<is> in a declaration.
 For information on variables without sigils, see
 L<sigilless variables|#Sigilless variables>.
 
-=head2 Item and List Assignment
+=head2 Item and list assignment
 
 There are two types of variable assignment, I<item assignment> and I<list
 assignment>.  Both use the equal sign C<=> as operator. The syntax of the
@@ -193,7 +193,7 @@ only depends on the C<$>.
 
 =end table
 
-=head2 The C<*> Twigil
+=head2 The C<*> twigil
 X<|$*>
 
 This twigil is used for dynamic variables which are looked up through the caller's, not through the outer,
@@ -256,7 +256,7 @@ boolean context before using it for anything else:
 Dynamic variables can have lexical scope when declared with C<my> or package scope when declared with C<our>. Dynamic resolution and resolution through symbol tables introduced with C<our> are two orthogonal issues.
 
 
-=head2 The C<?> Twigil
+=head2 The C<?> twigil
 X<|$?>
 
 Compile-time variables may be addressed via the C<?> twigil. They are known
@@ -270,7 +270,7 @@ example for this is:
 For a list of these special variables, see
 L<compile-time variables|/language/variables#Compile-time_variables>.
 
-=head2 The C<!> Twigil
+=head2 The C<!> twigil
 X<|$!>
 
 L<Attributes|/language/objects#Attributes> are variables that exist per instance
@@ -293,7 +293,7 @@ you though. For more details on objects, classes and their attributes see
 L<object orientation|/language/objects>.
 
 
-=head2 The C<.> Twigil
+=head2 The C<.> twigil
 X<|$.>
 
 The C<.> twigil isn't really for variables at all. In fact, something along
@@ -326,13 +326,13 @@ is also possible:
 For more details on objects, classes and their attributes and methods see
 L<object orientation|/language/objects>.
 
-=head2 The C<^> Twigil
+=head2 The C<^> twigil
 X<|$^>
 
-The C<^> twigil declares a formal positional parameter to blocks or
-subroutines.  Variables of the form C<$^variable> are a type of placeholder
-variable. They may be used in bare blocks to declare formal parameters to
-that block. So the block in the code
+The C<^> twigil declares a formal positional parameter to blocks or subroutines;
+that is, variables of the form C<$^variable> are a type of placeholder variable.
+They may be used in bare blocks to declare formal parameters to that block. So
+the block in the code
 
     my @powers-of-three = 1,3,9…100;
     say reduce { $^b - $^a }, 0, |@powers-of-three;
@@ -362,7 +362,7 @@ Placeholder variables cannot have type constraints or a variable name with a
 single upper-case letter (this is disallowed to enable catching some
 Perl5-isms).
 
-=head2 The C<:> Twigil
+=head2 The C<:> twigil
 X<|$:>
 
 The C<:> twigil declares a formal named parameter to a block or subroutine.
@@ -376,7 +376,7 @@ therefore not ordered using Unicode order, of course). So this:
 
 See L<^> for more details about placeholder variables.
 
-=head2 The C<=> Twigil
+=head2 The C<=> twigil
 X<|$=>
 
 The C<=> twigil is used to access Pod variables. Every Pod block in the
@@ -400,7 +400,7 @@ hierarchical data structure through C<$=pod>.
 Note that all those C<$=someBlockName> support the C<Positional> and the
 C<Associative> roles.
 
-=head2 The C<~> Twigil
+=head2 The C<~> twigil
 X<|$~>
 
 The C<~> twigil is for referring to sublanguages (called slangs). The
@@ -426,7 +426,7 @@ augment slang Regex {  # derive from $~Regex and then modify $~Regex
 }
 =end code
 
-=head1 Variable Declarators and Scope
+=head1 Variable declarators and scope
 
 Most of the time it's enough to create a new variable using the C<my>
 keyword:
@@ -457,7 +457,7 @@ predefined variables:
     temp    Restores a variable's value at the end of scope
     let     Restores a variable's value at the end of scope if the block exits unsuccessfully
 
-=head2 The C<my> Declarator
+=head2 The C<my> declarator
 
 Declaring a variable with C<my> gives it lexical scope. This means it only
 exists within the current block. For example:
@@ -520,7 +520,7 @@ variable using L<the * twigil|#The_*_Twigil>. This twigil makes the compiler loo
 C<my> is the default scope for subroutines, so C<my sub x() {}> and
 C<sub x() {}> do exactly the same thing.
 
-=head2 The C<our> Declarator
+=head2 The C<our> declarator
 
 C<our> variables work just like C<my> variables, except that they also
 introduce an alias into the symbol table.
@@ -573,7 +573,7 @@ To skip elements in the list use the anonymous state variable C<$>.
     say [$a, %h].perl;
     # OUTPUT: «["b", {:th(1)}]␤»
 
-=head2 The C<has> Declarator
+=head2 The C<has> declarator
 
 C<has> scopes attributes to instances of a class or role, and methods to
 classes or roles. C<has> is implied for methods, so C<has method x() {}>
@@ -582,7 +582,7 @@ and C<method x() {}> do the same thing.
 See L<object orientation|/language/objects> for more documentation and some
 examples.
 
-=head2 The C<anon> Declarator
+=head2 The C<anon> declarator
 
 The C<anon> declarator prevents a symbol from getting installed in the lexical
 scope, the method table and everywhere else.
@@ -597,7 +597,7 @@ but still aren't installed in a scope:
     say %operations<square>.name;       # square
     say %operations<square>(8);         # 64
 
-=head2 The C<state> Declarator
+=head2 The C<state> declarator
 
 C<state> declares lexically scoped variables, just like C<my>. However,
 initialization happens exactly once the first time the initialization
@@ -671,7 +671,7 @@ State variables are shared between all threads. The result can be unexpected.
     # many other more or less odd variations can be produced
 
 X<|anon state variables>X<|nameless variables>X<|$ (variable)>
-=head3 The C<$> Variable
+=head3 The C<$> variable
 
 In addition to explicitly declared named state variables, C<$> can be used
 as an anonymous state variable without an explicit C<state> declaration.
@@ -719,7 +719,7 @@ subset DynInt where $ = ::('Int'); # the initializer will be called for each typ
 subset DynInt where state $ = ::('Int'); # the initializer is called once, this is a proper cache
 =end code
 
-=head3 The C<@> Variable
+=head3 The C<@> variable
 
 Similar to the C<$> variable, there is also a L<Positional>
 anonymous state variable C<@>.
@@ -754,7 +754,7 @@ to do anything useful with it.
 As with C<$>, each mention of C<@> in a scope introduces a new anonymous
 array.
 
-=head3 The C<%> Variable
+=head3 The C<%> variable
 
 In addition, there's an L<Associative> anonymous state variable C<%>.
 
@@ -786,7 +786,7 @@ access is also possible (with copying to make it useful).
 As with the other anonymous state variables, each mention of C<%> within a
 given scope will effectively introduce a separate variable.
 
-=head2 The C<augment> Declarator
+=head2 The C<augment> declarator
 
 With C<augment>, you can add attributes and methods to existing classes and
 grammars, provided you activated the C<MONKEY-TYPING> pragma first.
@@ -805,7 +805,7 @@ are better solutions.
 (In this case, the better solution would be to use a
 L<function|/language/functions>).
 
-=head2 The C<temp> Prefix
+=head2 The C<temp> prefix
 
 Like C<my>, C<temp> restores the old value of a variable at the end of its
 scope. However, C<temp> does not create a new variable.
@@ -841,7 +841,7 @@ scope. However, C<temp> does not create a new variable.
     #           </g>
     #          </g>␤»
 
-=head2 The C<let> Prefix
+=head2 The C<let> prefix
 
 Restores the previous value if the block exits unsuccessfully. A
 successful exit means the block returned a defined value or a list.
@@ -864,9 +864,7 @@ stay as 84 because the block returns a defined value (C<say> returns
 true). Otherwise the C<die> statement will cause the block to exit
 unsuccessfully, resetting the answer to 42.
 
-=comment this is duplicated in operators.pod
-
-=head1 Type Constraints and Initialization
+=head1 Type constraints and initialization
 
 Variables have a type constraint via the L<container|/language/containers> they
 are bound to, which goes between the declarator and the variable name. The
@@ -902,7 +900,7 @@ re-applied by assigning C<Nil> to it:
     $product = Nil;
     say $product;                       # OUTPUT: «1␤»
 
-=head2 Default Defined Variables Pragma
+=head2 Default defined variables pragma
 
 To force all variables to have a L<definitness|/language/mop#index-entry-syntax_DEFINITE-DEFINITE>
 constraint, use the pragma C<use variables :D>. The pragma is lexically scoped and can be
@@ -931,7 +929,7 @@ As the name suggests, this pragma applies only to variables. To effect
 the same behaviour on parameters, use the C<use parameters :D> pragma
 (currently NYI in Rakudo).
 
-=head1 Special Variables
+=head1 Special variables
 
 Perl 6 attempts to use long, descriptive names for special
 variables. There are only three special variables that are extra
@@ -952,7 +950,7 @@ There are three special variables that are available in every block:
 =end table
 
 X<|topic variable>
-=head3 The C<$_> Variable
+=head3 The C<$_> variable
 
 C<$_> is the topic variable. It's the default parameter for blocks that do
 not have an explicit signature, so constructs like C<for @array { ... }> and
@@ -985,7 +983,7 @@ work on C<$_>:
     #          ij*␤»
 
 X<|match variable>
-=head3 The C<$/> Variable
+=head3 The C<$/> variable
 
 C<$/> is the match variable. It stores the result of the last
 L<Regex|/language/regexes>
@@ -1015,7 +1013,7 @@ say $/;
 #             textnode => ｢some text｣␤»
 =end code
 
-=head4 X«Positional Attributes|variable,$0;variable,$1;variable,@()»
+=head4 X«Positional attributes|variable,$0;variable,$1;variable,@()»
 
 C<$/> can have positional attributes if the L<Regex|/language/regexes> had
 capture-groups in it, which are just formed with parentheses.
@@ -1034,7 +1032,7 @@ C<@()> can be used.
 
     say @().join; # OUTPUT: «bbbbbdddddeff␤»
 
-=head4 X«Named Attributes|variable,$<named>;variable,%()»
+=head4 X«Named attributes|variable,$<named>;variable,%()»
 
 C<$/> can have named attributes if the L<Regex|/language/regexes> had named
 capture-groups in it, or if the Regex called out to another Regex.
@@ -1054,7 +1052,7 @@ be used.
     say %().join;       # OUTPUT: «"punctuation     ....final-word  see?"␤»
 
 X<|error variable>
-=head3 The C<$!> Variable
+=head3 The C<$!> variable
 
 C<$!> is the error variable. If a C<try> block or statement prefix catches
 an exception, that exception is stored in C<$!>. If no exception was caught,
@@ -1162,7 +1160,7 @@ C<:bin> will be set on the L<IO::ArgFiles> object.
 Arguments from the command line.
 
 X<|$*IN>X<|$*OUT>X<|$*ERR>
-=head3 Special Filehandles: STDIN, STDOUT and STDERR
+=head3 Special filehandles: C<STDIN>, C<STDOUT> and C<STDERR>
 
 For more information about special filehandles please see also the L<Input and
 Output|/language/io> page and the L<IO::Special> class. L<IO::Handle> contains
@@ -1178,7 +1176,7 @@ Standard output filehandle, AKA I<STDOUT>.
 =item C<$*ERR>
 Standard error filehandle, AKA I<STDERR>.
 
-=head3 Runtime Environment
+=head3 Runtime environment
 X<|%*ENV>
 =item  C<%*ENV>
 Environment variables;
@@ -1323,7 +1321,7 @@ default changed before using them:
 
 This behavior is not tested in the spec tests and is subject to change.
 
-=head1 Naming Conventions
+=head1 Naming conventions
 
 It is helpful to know our naming conventions in order to understand what codes
 do directly. However, there is not yet a conventions list covering anywhere.