' '  String literal
  Identifier
[ ]  Identifier
` `  Identifier
?    Numbered host parameter
:    Named host parameter
$    Named host parameter
@    Named host parameter
( )  Parentheses
+    Add
-    Subtract/negative
*    Multiply
/    Divide
%    Modulo
&    Bitwise AND
|    Bitwise OR
~    Bitwise NOT
<<   Left shift
>>   Right shift
=    Equal
==   Equal
<>   Not equal
!=   Not equal
<    Less
>    Greater
<=   Less or equal
>=   Greater or equal
||   String concatenation