As previously mentioned, IEG scripts are stored in the database. When an IEG script is executed, the IEG Engine checks the script definition to ensure that all scripts elements that require an "internal-id" have one assigned. If there are internal IDs missing, the script definition is modified to populate the missing IDs and is updated in the database. So the first time the script is executed, the internal IDs are set and should not be changed subsequently. The internal IDs are used by the IEG Engine to support script execution, for example they are used to determine what the current page in the script execution should be. In order for script executions to continue or for script executions to be resumed, the internal IDs in the script definition must be consistent with the internal IDs when the script execution was created. For this reason, it is important to ensure that the upgrade environment is in sync with the production environment.