Requirements for Vendor extensions to the ODM model are:
1. The vendor must supply a XML Schema fully describing their extended ODM format.
2. Extended ODM files should reference the proper extension Schema.
3. The extension may add new XML elements and attributes, but may not render any standard ODM elements or attributes obsolete. Vendor extensions cannot be used for information that is normally expressed using other ODM elements.
4. All new element and attribute names must use distinct XML namespaces to insure that there are no naming conflicts with other vendor extensions.
5. Removing all vendor extensions from an extended ODM file must result in a meaningful and accurate standard ODM file.
6. Vendors should be able to produce ODM files free of any vendor extensions upon request.
OpenClinica meets these requirements in its use of vendor extensions.