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| StudyOID | oidref | References the Study that provides a prior metadata version. | |
| MetaDataVersionOID | oidref | References the prior MetaDataVersion (within the above Study). | |
| href | URI | Reference to the location where the to be included Study-Metadata definition can be retrieved from. |
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When a metadata element such as an ItemDef is re-defined in a MetaDataVersion that includes a previous MetaDataVersion, any metadata element of the same type and with the same OID in a preceding MetaDataVersion is completely replaced. This includes all attributes and child elements. It also means that all attributes and child elements not present in the new definition are effectively deleted from the previous version.
The href attribute allows to provide the location (as a URL) to the ODM where the to-be-included elements can be retrieved from, in the case that the combination of the referenced study and metadataversion is not present in the same file. The reference can be to a file, e.g. "file:///d:/MyStudies/MyStudy/PriorVersionODM.xml" or e.g. be an API call, like "https://www.MyCompany.com/MyStudies?StudyOID=MyStudy&MetaDataVersionOID=MV.001".
In the following example, question "I.003" has been added to the ItemGroup "IG.001" by adding an ItemRef element to the ItemGroupDef. The new version of the ItemGroupDef now contains only one of the Aliases, and the other Alias defined in MetaDataVersion "MDV.001" has been removed. This same mechanism is used to remove ItemRefs from an ItemGroupDef, or to re-order them.
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