TRUE if there is an error in the order of the IDs, FALSE if not.
FUNCTION
The function calls the check_incr_ids function for all input units
(having the UnitFlag field set to INUNIT) and check_decr_ids for
all output units (having the UnitFlag field set to OUTUNIT).
NOTE
This function is used by check_ff_net.
The function may be quite time-consuming for large networks, since all paths
from an input unit to an output unit and vice versa are checked.