Accessing Files Programmer's Guide (32650-90885)

Chapter 2 23
Creating A File
The HPFOPEN Intrinsic
control parameter in the call to FWRITE, or by sending the control code
directly through the
control parameter of FWRITE.
If a carriage-control character is sent to a file where the control cannot be
executed directly (for example, line spacing characters sent to a disk or
tape file), the control character is embedded as the first byte of the record.
Therefore, the first byte of each record in a disk file having carriage-control
characters enabled contains control information. If carriage-control
characters are sent to other types of files, the control is transmitted to the
driver.
Control codes %400 through %403 are remapped to %100 through %103,
so that they fit into one byte and can be embedded. Records written to the
line printer with control codes %400 through %403 should contain only
control information.
Records written with control codes %400 through %403 and no data
(count=0, or embedded control and count=1) does not cause physical I/O.
For computing record size, the file system considers carriage-control
information as part of the data record. Therefore, specifying the
carriage-control option adds one byte to the record size when the file is
originally created. For example, a specification of
REC=-132,1,F,ASCII;CCTL results in a
recsize of 133 bytes.
Generally, the entire record can be read. Refer to the table listing the item
values returned by the FFILEINFO intrinsic. However, on writes to files
where carriage-control characters are specified, the data transferred is
limited to
recsize -1 unless a control of one is passed, indicating the data
record is prefixed with embedded carriage-control characters.
The value of this
itemnum is ignored when a byte stream or hierarchical
directory is created. Byte stream files and hierarchical directories are
created without carriage control (NOCCTL).
8/CA Enable tape label:
Passes the tape label name of a labeled tape. The name must follow the
ANSI standards for tape label names. The name consists of <=6 printable
characters that identify the volume. In a multivolume set, only the first
tape label can be specified.
Default: a null tape label
A character placed in the first element designates the delimiter used by
HPFOPEN to search for the end of the character array. The delimiter can
appear again only following the last valid character of the character array,
for example:
%volid% (% is the delimiter, volid is the designator)
fabcxyzf ( f is the delimiter, abcxyz is the designator)
(ASC) Not used for asynchronous devices.
9/I32 Disallow file equation: