
Defect list handling implemented up to now uses DiscSize
and DiscSize2 to determine whether to use a single or
a twin defect list.  This mechanism may fail with discs
partitioned for Risc iX or other Unix systems, so from
now on will use the new BigFlag field to determine this.

Files and routines thought to need changing (list is
incomplete and may grow).

File            Routine                         Status

s.Commands      UpdateBadBlockList              Done
s.FileCore60    DoOsFunDefectList64             Done
