Search Condition

<search_condition> ::= <boolean_term> 
                     | <search_condition> {OR | XOR} <boolean_term>

<boolean_term> ::= <boolean_factor> | <boolean_term> AND <boolean_factor>

<boolean_factor> ::= [NOT] <boolean_primary>

<boolean_primary> ::= <value_expression> <comp_op> <value_expression>
                    | ISEMPTY(<value_expression>)
                    | (<search_condition>)

<comp_op> ::= <equals_operator>
            | <not_equals_operator>
            | <less_than_operator>
            | <greater_than_operator>
            | <less_than_or_equals_operator>
            | <greater_than_or_equals_operator>

<equals_operator> ::= =

<not_equals_operator> ::= <>

<greater_than_operator> ::= >

<less_than_operator> ::= <

<greater_than_or_equals_operator> ::= >=

<less_than_or_equals_operator> ::= <=