CONTENTdm® is a digital object repository system based around the concepts of "objects" (often called "items") and "collections." An object is a combination of digital primary data - typically in the form of a file on disk - and metadata. It must reside in a collection. It has an ascending-integer identifier called a "pointer" ("CISOPTR"), which will uniquely identify it within a collection; but this is not a global identifier, as objects in different collections may have the same pointers. To globally identify an object, the combination of a collection alias (see below) and pointer must be used.
Collections can contain any number of objects, but they cannot contain other collections. A collection has a name and a unique identifier, called an "alias" (or "CISOROOT"), which is a brief string prefixed with a slash. It has a metadata template, which defines the set of Dublin Core metadata elements that are available to be used by objects in the collection and how they are to be sorted, searched, named, mapped, and so on.
CONTENTdm® supports a special type of object called a compound object. This is actually an amalgamation of several independent objects into one whole. A compound object consists of a single "master" or "parent" object associated with zero or more "pages," which are themselves objects.