Depending on how your data came in and how you generated triples for it the last step before importing the information into VIVO is to give your data proper URIs via the ChangeNamespace tool. Prior to this step, URIs may be placeholders provided by the XSLT translation (typically using aspects of the raw data that are expected to be unique, such as an ISBN number) or blank nodes from a SPARQL Construct.  If you've generated unique URI's for all of your data using a piece of unique information then you can skip this step. After this step all data has a proper VIVO URI and is ready for import into VIVO.