A particular complication with online material is its flexibility. Information can be easily changed after it has been reviewed. Ideally, sites should be reviewed regularly to see whether they still meet the criteria for inclusion. However, in practice this will often not be realizable. After sites have been reviewed and judged appropriate for inclusion, they are classified and annotated.
Classification is both a very important and a very difficult task.
The classification scheme of the Virtual Library has evolved over time, and is far from perfect. A new classification scheme is under development in collaboration with the librarian of the European Documentation Centre and Observatory on Migration and Ethnic Relations. And in addition to the current resource categories that are primarily based on characteristics of the suppliers of information, a second categorization is planned based on the subject or content of information available on websites. In order to offer more than just a list of links , short descriptions have been added to hyperlinks in the Virtual Library. Sometimes these descriptions are supplied by maintainers of sites themselves, or taken from online self presentations.