A DTS package is uniquely identified by the combination of a package ID (GUID) and version ID (GUID). The package ID is assigned when the package is created. The version ID is assigned when the package is first saved or executed. Initially, the package ID and version ID are equal. However, the version ID is assigned a new value any time the package is executed or saved.
When a package is saved to a COM-structured storage file, each package version is saved in a separate storage area as substorage under the package ID. Each package version contains substorage for tasks, steps, connections, and global variable collections, all stored in a separate stream using the IStorage interface. Package versions are saved to msdb when a package is saved to Microsoft® SQL Server™ storage or Microsoft Repository.
Each package is saved in a separate storage area off the root storage in transacted mode to protect consistency of the package definition. Changes are not committed until all substorage has been written successfully.