If a field within a record in an externally described file is to be renamed,
enter the external name of the field in these positions. A field may have
to be renamed because the name is the same as a field name specified in the
program and two different names are required.
Note: If the input field is for a file that has the PREFIX
keyword coded, and the prefixed name has already been specified in the Field
Name entry (positions 49 - 62) of a prior Input specification for the same
record, then the prefixed name must be used as the external name. For more
information, see
PREFIX(prefix{:nbr_of_char_replaced}).