Works that are the main focus or most important in a complex work or project; used to distinguish primary works from auxiliary or accessory works; the concept may apply to a wide variety of disciplines. In cataloging, the work is typically assumed to be a primary work, requiring clarification only when there is also an ancillary work. An example would be an office building, which is a primary architectural work having as an ancillary work the heating system. The concept may also refer to the status of separate, independent works, which may be grander or more important than other separate, independent "secondary works."
