To lock multiple records, using manual record locking:
 select fd-name
     assign to "muser.dat"
     lock mode is manual with lock on multiple records.
  ...
     read fd-name with kept lock
To lock multiple records, using automatic record locking:
 select fd-name
     assign to "muser.dat"
     lock mode is automatic with lock on multiple records.
  ...
     read fd-name