By default, the AllowDefaultOperators property is True, which indicates that expression supports all default operators. The AllowDefaultOperators property specifies whether the expression supports default operators. For instance, you can disable all constants and operators by setting the AllowDefaultOperators property on False. The AllowValueKeyword property specifies whether the expression supports the value keyword. The AddCustomOperator method allows you to add custom operators. The ClearCustomOperators method clears the custom operators.