The 'persistent children' subgroup must occur before the 'temporary children' subgroup. Persistent references are defined in the 'persistent children' subgroup while temporary references are defined in the 'temporary children' subgroup. The CELL record is followed by a group containing the references for the cell, organized into subgroups. They follow the same format in both cases.
CELL records contain the data for either interior (CELL top group) or exterior (WRLD top group) cells.
