The DISKQUOTA MODIFY command changes values in a quota file for
    the disk named in the device specification. If you establish a
    quota limit that is less than the current usage count, a user can
    still log in and out, but cannot create files.

    After creating a quota file, use the DISKQUOTA MODIFY command to
    set default values for quotas and overdrafts. UIC [0,0] sets the
    default permanent quota and overdraft values for a quota file,
    so you must change the entry [0,0] to values appropriate for
    your installation. Unless you specify quota and overdraft values
    when adding a file entry, SYSMAN applies these defaults to UIC
    entries.