enum OdDgExpressionItemType { kUnknown = 0, kConstant = 1, kVariable = 2, kAdd = 3, kSubtract = 4, kMultiply = 5, kDivide = 6, kExponent = 7, kGroup = 8, kNegative = 9, kFunction = 10, kSpecialConst = 11, kCondition = 12, kAnd = 13, kOr = 14, kNot = 15, kEqualOrNot = 16, kCompare = 17, kModulo = 18, kVariableId = 255 };