The process of registering a data model as common data elements annotated with terms from a controlled vocabulary in caBIG. The key concepts in harmonization are: 1) data model elements (attributes) are annotated with terms from a controlled vocabulary, so that their semantic meaning is well defined, and 2) existing common data elements are reused, when appropriate, to represent the elements of the data model so that semantically equivalent information is expressed in the same way in this and other data models.