develop flags are settable / visible only during development and are constant in the PRODUCT version
notproduct flags are settable / visible only during development and are not declared in the PRODUCT version
diagnostic options not meant for VM tuning or for product modes. They are to be used for VM quality assurance or field diagnosis of VM bugs. They are hidden so that users will not be encouraged to try them as if they were VM ordinary execution options. However, they are available in the product version of the VM. Under instruction from ... (全文...)