The ASSOCIATEVARIABLE specifier indicates a variable that is updated after each direct access I/O operation, to reflect the record number of the next sequential record in the file. It takes the following form:

asv

Is a scalar integer variable. It cannot be a dummy argument to the routine in which the OPEN statement appears.

Direct access READs, direct access WRITEs, and the FIND, DELETE, and REWRITE statements can affect the value of asv.

The BLOCKSIZE specifier specifies the physical I/O transfer size for the file. It takes the following form:

bks

Is a scalar numeric expression. If necessary, the value is converted to integer data type before use.

For magnetic tape files, the value of bks specifies the physical record size in the range 18 to 32767 bytes. The default value is 2048 bytes.

For sequential disk files, the value of bks is rounded up to an integral number of 512-byte blocks and used to specify multiblock transfers. The number of blocks transferred can be 1 to 127; it is determined by RMS defaults.

The BUFFERCOUNT specifier indicates the number of buffers to be associated with the unit for multibuffered I/O. It takes the following form:

bc

Is a scalar numeric expression in the range 1 through 127. If necessary, the value is converted to integer data type before use.

The BLOCKSIZE specifier determines the size of each buffer. For example, if BUFFERCOUNT=3 and BLOCKSIZE=2048, the total number of bytes allocated for buffers is 3*2048, or 6144.

The BUFFERED specifier indicates run-time library behavior following WRITE operations. It takes the following form:

bf

Is a scalar default character expression that evaluates to one of the following values:

' NO '	Requests that the run-time library send output data to the file system after each WRITE operation.
' YES '	Requests that the run-time library accumulate output data in its internal buffer, possibly across several WRITE operations, before the data is sent to the file system. Buffering may improve run-time performance for output-intensive applications.

The default is ' NO ' .

The CARRIAGECONTROL specifier indicates the type of carriage control used when a file is printed. It takes the following form:

cc

Is a scalar default character expression that evaluates to one of the following values:

' FORTRAN '	Indicates normal Fortran interpretation of the first character.
' LIST '	Indicates one line feed between records.
' NONE '	Indicates no carriage control processing.

The CONVERT specifier indicates a nonnative numeric format for unformatted data. It takes the following form:

fm

Is a scalar default character expression that evaluates to one of the following values:

' LITTLE_ENDIAN ' 1	Little endian integer data 2 and IEEE floating-point data. 3
' BIG_ENDIAN ' 1	Big endian integer data 2 and IEEE floating-point data. 3
' CRAY '	Big endian integer data 2 and CRAY floating-point data of size REAL(8) or COMPLEX(8).
' FDX '	Little endian integer data 2 and VAX floating-point data of format F_floating for REAL(4) or COMPLEX(4), D_floating for size REAL(8) or COMPLEX(8), and IEEE X_floating for REAL(16) or COMPLEX(16).
' FGX '	Little endian integer data 2 and VAX floating-point data of format F_floating for REAL(4) or COMPLEX(4), G_floating for size REAL(8) or COMPLEX(8), and IEEE X_floating for REAL(16) or COMPLEX(16).
' IBM '	Big endian integer data 2 and IBM System\370 floating-point data of size REAL(4) or COMPLEX(4) (IBM short 4), and size REAL(8) or COMPLEX(8) (IBM long 8).
' VAXD '	Little endian integer data 2 and VAX floating-point data of format F_floating for size REAL(4) or COMPLEX(4), D_floating for size REAL(8) or COMPLEX(8), and H_floating for REAL(16) or COMPLEX(16).
' VAXG '	Little endian integer data 2 and VAX floating-point data of format F_floating for size REAL(4) or COMPLEX(4), G_floating for size REAL(8) or COMPLEX(8), and H_floating for REAL(16) or COMPLEX(16).
' NATIVE '	No data conversion. This is the default.

You can use CONVERT to specify multiple formats in a single program, usually one format for each specified unit number.

When reading a nonnative format, the nonnative format on disk is converted to native format in memory. If a converted nonnative value is outside the range of the native data type, a run-time message appears.

There are other ways to specify numeric format for unformatted files: you can specify an OpenVMS logical name, the command line qualifier /CONVERT, or OPTIONS/CONVERT. The following shows the order of precedence:

The /CONVERT qualifier and OPTIONS/CONVERT affect all unit numbers used by the program, while logical names and OPEN (CONVERT=) affect specific unit numbers.

The following example shows how to code the OPEN statement to read unformatted CRAY numeric data from unit 15, which might be processed and possibly written in native little endian format to unit 20:

 OPEN (CONVERT='CRAY', FILE='graph3.dat', FORM='UNFORMATTED',
1     UNIT=15)
     .
     .
     .
 OPEN (FILE='graph3_native.dat', FORM='UNFORMATTED', UNIT=20)

The DEFAULTFILE specifier indicates a default file specification string. It takes the following form:

def

Is a character expression indicating a default file specification string.

This specifier can supply a value to the RMS default file specification string for the missing components of a file specification. If you omit the DEFAULTFILE specifier, HP Fortran uses the default value "FORnnn.DAT", where nnn is the unit number with leading zeros.

The default file specification string is used primarily when accepting file specifications interactively. Complete file specifications known to a user program normally appear in the FILE specifier.

You can indicate default values for any one of the following file-specification components:

• Node
• Device
• Directory
• File name
• File type
• File version number