Intel(R) Fortran Compiler for Linux* Systems User's Guide Volume I ...

Intel® Fortran Compiler for Linux* Systems User's Guide Volume I: Building
Applications
• Add records sequentially by using multiple WRITE statements, close the
file, and then open it again with ORGANIZATION= ' SEQUENTIAL ' and
ACCESS= ' SEQUENTIAL ' (or ACCESS= ' DIRECT ' if the sequential file
has fixed-length records).
Sequential Access
Sequential access transfers records sequentially to or from files or I/O devices
such as terminals. You can use sequential I/O with any type of supported file
organization and record type.
If you select sequential access mode for files with sequential or relative
organization, records are written to or read from the file starting at the beginning
of the file and continuing through it, one record after another. A particular record
can be retrieved only after all of the records preceding it have been read; new
records can be written only at the end of the file.
Direct Access
Direct access transfers records selected by record number to and from either
sequential files stored on disk with a fixed-length record type or relative
organization files.
If you select direct access mode, you can determine the order in which records
are read or written. Each READ or WRITE statement must include the relative
record number, indicating the record to be read or written.
You can directly access a sequential disk file only if it contains fixed-length
records. Because direct access uses cell numbers to find records, you can enter
successive READ or WRITE statements requesting records that either precede
or follow previously requested records. For example, the first of the following
statements reads record 24; the second reads record 10:
READ (12,REC=24) I
READ (12,REC=10) J
Limitations of Record Access by File Organization
and Record Type
You can use both access modes on sequential and relative files. However, direct
access to a sequential organization file can only be done if the file resides on
disk and contains fixed-length records.
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