From YourAssociationWiki

Cantilever rack, courtesy of CICMHE/MHIA Multimedia Bank

Cantilever rack is rack that utilizes "arms" cantilevered from columns, and is used where there is a need for a full clear shelf that can be loaded from the front without obstruction from rack support uprights.^[1]

References

1. http://www.mhia.org/learning/glossary