COBOL Manual for TNS/E Programs (H06.08+, J06.03+)

15 PART-TIME PICTURE 99.
15 FULL-TIME PICTURE 99.
10 EXEMPT PICTURE 9(4).
...
01 MISC-RECORD.
...
Records
A record is a sequence of character positions. It can be an elementary data item or a data structure.
Its data description entry determines its internal structure (see PICTURE Clause (page 191)). Records
can be of fixed length or variable length. COBOL programs manipulate logical records and physical
records.
Most of the data in a typical COBOL program is in records. When a program reads data from or
writes data to a file, the unit of transmission is the record.
Topics:
• Physical Records and Logical Records
• Record Elements
• Record Length
NOTE: In this manual, “record” means logical record unless “physical record” is specified.
Physical Records and Logical Records
COBOL programs manipulate physical records and logical records. A physical record is a physical
unit of information whose size and recording mode is convenient to a particular computer for the
storage of data on an input or output device (such as 80 characters for a terminal or 132 characters
for a printer). The size of a physical record is hardware dependent and bears no direct relationship
to the size of the file of information contained on a device. A physical record can contain one or
several logical records, or a logical record can span several physical records.
A logical record is a group of related information, uniquely identifiable, and handled as a unit.
The number of logical records that can exist in a file is a characteristic of its supporting storage
medium, possibly modified by instructions presented to the file system during the file’s creation.
The logical records of a file have either a fixed size or a size that varies between a maximum and
minimum size, depending on record type.
A logical record is defined by a set of data description entries. Each entry has a level-number
followed by a data-name and possibly a series of independent clauses. The level-numbers form a
structure, dividing a record into smaller and smaller parts.
Example 13 Logical Record
01 BIBLIOGRAPHY-RECORD.
03 AUTHOR-NAME.
05 LAST-NAME PICTURE X(20).
05 FIRST-NAME PICTURE X(20).
03 TITLE PICTURE X(50).
03 PUBLICATION-INFO.
05 PUBLISHER.
07 PUB-NAME PICTURE X(20).
07 PUB-LOCATION PICTURE X(20).
05 PUBLICATION-YEAR PICTURE 9999.
The concept of logical records also applies to data outside files. You can group data into logical
records in all sections of the Data Division.
Data Structures 79