Using edit bounds with variable-length records
The location of the right edit bound governs the behavior of the (and) (shift left and shift right) line commands with variable-length records. If the right bound "touches" a record being shifted (for example, the right bound has a value less than or equal to the current length of the record), the data between the bounds is shifted and the length of the record is not affected.
If the right bound is located beyond the current end of a record, executing a right shift line command increases the record length by the number of columns shifted, up to the limit defined by the right bound. The length cannot exceed the record length specified when the data set was allocated. A left shift similarly decreases the record length, to a minimum length defined by the left edit bound.
For information on modifying the length of a variable-blocked record, see Character Mode.