contract Consideration is ConsiderationInterface, OrderCombiner {
    function fulfillBasicOrder(BasicOrderParameters calldata parameters) ... {
        ...
        fulfilled = _validateAndFulfillBasicOrder(parameters);
    }
}
contract BasicOrderFulfiller is OrderValidator {
    function _validateAndFulfillBasicOrder(  BasicOrderParameters calldata parameters ) internal returns (bool) {
        ...   // as the parameters are calldata, no checks on out of bound is done
        BasicOrderRouteType route;
        ItemType receivedItemType;
        ...
        assembly {
            ...
            route := div(calldataload(BasicOrder_basicOrderType_cdPtr), 4) // doesn't check for out of range values
            ...
            receivedItemType := add( // if route == 6, then receivedItemType == 4 == ERC721_WITH_CRITERIA
                mul(sub(route, 2), gt(route, 2)), // (6-2) * 1 == 4
                eq(route, 2)                      // + 0 == 4  // this is a valid ItemType 
        )
        ...
        if (additionalRecipientsItemType == ItemType.NATIVE) {   // this is luckily false
        ...          
        } else {
            ...           
            if (route == BasicOrderRouteType.ERC20_TO_ERC721) {  // this catches the out of range value
                ...
            }
        }
    }
}
