⟩ Explain MDT?
MDT is a internal indicator.It is used when we are using
SFLNXTCHG in SFL.MDT indicator default in on mode.
breifly when we are using readc for read changed
records.MDT is internally on for every record .If retreive
the record once MDT is going to be off.for that purpose we
used SFLNXTCHG keyword to seton.