The DEFINE PARTITION command creates a partition. Partitions are
    the means by which you control elements.

    When you control an element, you identify the partition, which is
    called the base partition, in which a public, immutable copy of
    this element resides. CDO provides two ways to control elements,
    as follows:

    o  On an element-by-element basis, with the CONSTRAIN command.
       CDO controls the element that appears within the command.

    o  Through a context with the DEFINE CONTEXT and SET CONTEXT
       commands. Once you set the context, CDO controls all
       subsequent elements until the context is changed.

    Once an element has been controlled, you use the RESERVE and
    REPLACE commands to create subsequent versions. This reservation
    system prevents uncontrolled changes to elements.

    You can link partitions together to control change in various
    stages of a project. Each partition then represents a higher
    level of approval, or completion, in the overall partition
    hierarchy. The PROMOTE command moves elements higher within the
    hierarchy.

    The PARENT_PARTITION clause in the DEFINE PARTITION command
    creates a partition hierarchy by linking partitions in a parent-
    child relationship. The first, or root, partition does not have
    a parent partition. The second partition in the hierarchy has
    the first partition as its parent, and so on down the hierarchy.
    This clause can be specified only once during the lifetime of
    the partition, in either the DEFINE PARTITION or CHANGE PARTITION
    command.

    The LOOKASIDE_PARTITION clause makes the contents of another
    partition visible, provided that you have read privileges for
    the partition. You can read, but you cannot reserve, replace, or
    change the contents.

    The AUTOPURGE keyword ensures that CDO automatically purges
    intermediate versions of elements in the partition when you
    promote the latest version. The NOAUTOPURGE keyword prevents
    this automatic purging.