The PURGE command deletes all but the first and last version of
    an element. You cannot delete the first version, and intermediate
    versions are not purged if a branch line descends from them, or
    if they are children in a dependency relationship.

    You can only purge one line of descent at a time. Purge branch
    lines before main lines.

    You must specify a name of an element, or if you are using the
    PURGE ALL command, use the asterisk (*)  wildcard character.