EXPRESSION OPERATORS

 PPL allows the following operators to be used in expressions
 (lvalue and rvalue are simply the values to the left and right,
 respectively, of binary operators):

 (  - Start sub-expression (also allows [ or { to be used)
 )  - End sub-expression (also allows ] or } to be used)
 ^  - Raise lvalue to the power of rvalue
 *  - Multiply lvalue by rvalue
 /  - Divide lvalue by rvalue
 %  - Remainder of lvalue divided by rvalue
 +  - Add rvalue to lvalue
 -  - Subtract rvalue from lvalue
 =  - Is lvalue equal to rvalue (also allows ==)
 <> - Is lvalue not equal to rvalue (also allows != and ><)
 <  - Is lvalue less than rvalue
 <= - Is lvalue less than or equal to rvalue (also allows =<)
 >  - Is lvalue greater than rvalue
 >= - Is lvalue greater than or equal to rvalue (also allows =>)
 !  - Logical not of rvalue
 &  - Logical and of lvalue with rvalue (also allows &&)
 |  - Logical or of lvalue with rvalue (also allows ||)