List of Parser Tokens

In the above table of Tokens, it's worth noting that the bracketed text of "available as of PHP x.y.z" can mean one of two things:

[] This *parser token* is available as of PHP x.y.z
    {eg. T_BAD_CHARACTER, T_NAME_QUALIFIED}

[] This *language feature* is available as of PHP x.y.z
    {eg. T_ATTRIBUTE, T_COALESCE_EQUAL}

T_ENCAPSED_AND_WHITESPACE is whitespace which intersects a group of tokens. For example, an "unexpected T_ENCAPSED_AND_WHITESPACE" error is produced by the following code:

<?php
$main_output_world = 'snakes!';
echo('There are' 10 $main_output_world);
?>

Note the missing concatenation operator between the two strings leads to the whitespace error that is so named above. The concatenation operator instructs PHP to ignore the whitespace between the two code tokens (the so named "encapsed" data"), rather than parse it as a token itself.

The correct code would be:

<?php
$main_output_world = 'snakes!';
echo('There are' . 10 . $main_output_world);
?>

Note the addition of the concatenation operator between each token.

T_ENCAPSED_AND_WHITESPACED is returned when parsing strings with evaluated content, like "some $value" or this example from the Strings reference page:

<?php
echo <<<EOT
My name is "$name". I am printing some $foo->foo.
Now, I am printing some {$foo->bar[1]}.
This should print a capital 'A': \x41
EOT;
?>

This last example is tokenized as:
T_ECHO 
  echo
T_WHITESPACE 
  %20 (a space character)
T_START_HEREDOC 
  << 
T_ENCAPSED_AND_WHITESPACE 
  My name is "
T_VARIABLE
  $name
T_ENCAPSED_AND_WHITESPACE    
  ". I am printing some 
T_VARIABLE    
  $foo
T_OBJECT_OPERATOR    
  ->
T_STRING    
  foo
T_ENCAPSED_AND_WHITESPACE    
  . Now, I am printing some 
T_CURLY_OPEN    
  {
T_VARIABLE    
  $foo
T_OBJECT_OPERATOR    
  ->
T_STRING    
  bar
(terminal)
  [
T_LNUMBER    
  1
(terminal)
  ]
(terminal)
  }
T_ENCAPSED_AND_WHITESPACE    
  . This should print a capital 'A': \x41
T_END_HEREDOC
  EOT
(terminal)
  ;