TOPS-20 PASCAL Language Manual - Bitsavers

INPUT AND OUTPUT
7.7.1 File History -- NEW, OLD, READONLY, or UNKNOWN
The file status indicates whether the specified file exists or must be
created. The possible values are:
NEW
OLD
HEADONLY
UNKNOWN
A file status of NEW indicates that a new file must be created with
the specified attributes. NEW is the default value.
If you specify OLD, the system tries to open an existing file. An
error occurs if the file cannot be found. OLD is invalid for internal
files, which are newly created each time the declaring program or
subprogram is executed.
A file status of READONLY indicates that an existing file is being
opened only for reading. An error occurs if you try to write to a
file that has been opened with READONLY.
If you specify UNKNOWN, the system first tries to open an existing
file. If an existing file cannot be found, a new file is created with
the specified attributes.
If you specify READONLY, the system generates an error if a REWRITE is
performed on the file. READONLY implies OLD.
7.7.2 Record Length
The record length parameter specifies the record length used in the
file. Any positive integer can be used.
7.7.3 Record Access Mode -- SEQUENTIAL or DIRECT
The record access mode specifies the access to the components of the
file. The modes are:
DIRECT
SEQUENTIAL
In SEQUENTIAL mode, you can access files with fixedvariable-length
records. The default access mode is SEQUENTIAL.
or
DIRECT mode allows you to use the FIND procedure to access files with
fixed-length records. You cannot access a file with variable-length
records in DIRECT mode.
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