ACCESS

acc Is a character expression with one of the following values:

'DIRECT' Access by record number 'SEQUENTIAL' Access sequentially (*DEFAULT*) 'KEYED' Access by a specified key 'APPEND' Access sequentially, after the last record of the file

ASSOCIATEVARIABLE

asv Is an integer variable. It cannot be a dummy argument to the routine in which the OPEN statement appears. Use only in direct access mode.

NOTE: Direct access READ, direct access WRITE, FIND, DELETE, and REWRITE statements can affect the value of the variable.

BLANK

blnk Is a character expression with one of the following values:

'NULL' Ignore all blanks in a numeric field (unless the field is all blanks, in which case treat blanks as zero).

'ZERO' Treat all blanks other than leading blanks as zeros.

The default is 'NULL'. However, if you specify the /NOF77 compiler option (or OPTIONS /NOF77), the file is implicitly opened, or the file is opened for internal I/O, the default is 'ZERO'.

BLOCKSIZE

bks Is a numeric expression whose value specifies a number of bytes.

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, "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, and defaults to the current count for the device at program run time.

For indexed and relative files, "bks" is rounded up to an integral number of 512-byte blocks and used to specify the RMS bucket size. This must fall in the range 1 to 63 blocks, and defaults to the smallest value capable of holding one record.

BUFFERCOUNT

bc Is a numeric expression whose value specifies the number of buffers to be associated with the logical unit for multibuffered I/O. The range for "bc" is 1 to 127.

If you do not specify BUFFERCOUNT or you specify 0, the system default is assumed.

CARRIAGECONTROL

cc Is a character expression with one of the following values:

'FORTRAN' Process with normal FORTRAN interpretation of the first character 'LIST' Process with single spacing between records 'NONE' Do not use implied carriage control

The default for unformatted files is 'NONE'. The default for formatted files is 'FORTRAN'.

CONVERT

fm Is a character expression with one of the following options:

'LITTLE_ENDIAN'- Little endian integer data of the appropriate size (INTEGER*1, INTEGER*2, or INTEGER*4) and IEEE floating-point data of the appropriate size and type (REAL*4, REAL*8, COMPLEX*8, COMPLEX*16). INTEGER*1 data is the same for little endian and big endian.

'BIG_ENDIAN' - Big endian integer data of the appropriate size (INTEGER*1, INTEGER*2, or INTEGER*4) and IEEE floating-point data of the appropriate size and type (REAL*4, REAL*8, COMPLEX*8, COMPLEX*16). INTEGER*1 data is the same for little endian and big endian.

'CRAY' - Big endian integer data of the appropriate size (INTEGER*1, INTEGER*2, or INTEGER*4) and CRAY floating-point data of size REAL*8 or COMPLEX*16.

'IBM' - Big endian integer data of the appropriate size (INTEGER*1, INTEGER*2, or INTEGER*4) and IBM System\370 floating-point data of size REAL*4 or COMPLEX*8 (IBM short 4) and size REAL*8 or COMPLEX*16 (IBM long 8).

'VAXD' - Little endian integer data of the appropriate size (INTEGER*1, INTEGER*2, or INTEGER*4) and Digital VAX floating-point data of format F_floating for size REAL*4 or COMPLEX*8, and D_floating for size REAL*8 or COMPLEX*16.

'VAXG' - Little endian integer data of the appropriate size (INTEGER*1, INTEGER*2, or INTEGER*4) and Digital VAX floating-point data of format F_floating for size REAL*4 or COMPLEX*8, and G_floating for size REAL*8 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 non-native format, the non-native format on disk is converted to native format in memory. If a converted non-native 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 a VMS logical name or the compiler option CONVERT (or OPTIONS/CONVERT). The order of precedence is VMS logical name, OPEN (CONVERT=), OPTIONS/CONVERT, and then compiler option CONVERT. The CONVERT compiler option and OPTIONS/CONVERT affect all unit numbers used by the program, while logical names and OPEN (CONVERT=) affect specific unit numbers.

The following source code shows how to code the OPEN statement to read unformatted CRAY numeric data from unit 15, which might be processed and possibly written in 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)

For more information on transporting data to or from a VAX OpenVMS system and on supported ranges for data types, see your user manual.

DEFAULTFILE

ce Is a character expression that specifies a default file specification string.

This keyword supplies a value to the RMS default file specification string for the missing components of a file specification. If you do not specify the DEFAULTFILE keyword, Fortran uses the default value 'FORnnn.DAT', where nnn is the unit number with leading zeros.

The default file pathname string is used primarily when accepting file specifications interactively. File specifications known to a user program are normally completely specified in the FILE keyword.

You can specify default values for any one of the following file specification components: node, device, directory, file name, file type, and file version number.

When you specify any of the above components in the FILE keyword, they override those values specified in the DEFAULTFILE keyword.

The following example uses the file name supplied by the user and the default file specification supplied by the DEFAULTFILE keyword to define the file specification for an existing file:

TYPE *, 'ENTER NAME OF DOCUMENT' ACCEPT *, DOC OPEN (UNIT=1, FILE=DOC, DEFAULTFILE='[ARCHIVE].TXT', 1 STATUS='OLD')

DISPOSE

dis Is a character expression with one of the following values:

'KEEP' or 'SAVE' Retain the file after the unit is closed. (*DEFAULT FOR ALL BUT SCRATCH FILES*)

'DELETE' Delete the file after the unit is closed. (*DEFAULT FOR SCRATCH FILES*)

'PRINT' Submit the file as a print job and retain it. Use this value only with sequential files.

'PRINT/DELETE' Submit the file as a print job and then delete it. Use this value only with sequential files.

'SUBMIT' Submit the file as a batch job and retain it.

'SUBMIT/DELETE' Submit the file as a batch job and then delete it.

The disposition specified in a CLOSE statement supersedes the disposition specified in the OPEN statement, except that a file opened as a scratch file cannot be saved, printed, or submitted, nor can a file opened for read-only access be deleted.

ERR

s Is the label of an executable statement that is to receive control when an error occurs.

ERR applies only to the OPEN statement in which it is specified, and not in following I/O operations on the unit. If an error occurs, no file is opened or created. However, you can use IOSTAT in following I/O statements to perform a similar function.

EXTENDSIZE

e Is a numeric expression whose value specifies the number of blocks to extend a disk file when additional file storage is allocated. The space used to extend a file is contiguous if possible otherwise, noncontiguous space is used. Defaults to the system default for the device.

FILE

fln Is a character scalar reference, numeric scalar memory reference, or numeric array name reference.

The FILE parameter specifies the name of the file to be connected to the unit. The name can be any file specification accepted by the operating system.

If the file name is stored in a numeric scalar or array, the name must consist of ASCII characters terminated by an ASCII null character (zero byte). However, if it is stored in a character scalar or array, it must not contain a zero byte.

FORM

ft Is a character expression with one of the following values:

'FORMATTED' Formatted *DEFAULT FOR SEQUENTIAL ACCESS* 'UNFORMATTED' Unformatted *DEFAULT FOR DIRECT AND KEYED ACCESS*

INITIALSIZE

e Is a numeric expression whose value specifies the number of blocks in the initial allocation of space for a new file on a disk. Defaults to no initial allocation.

If you do not specify INITIALSIZE or if you specify zero, no initial allocation is made. The system attempts to allocate contiguous space for INITIALSIZE. If not enough contiguous space is available, noncontiguous space is allocated.

INITIALSIZE is effective only at the time the file is created. If EXTENDSIZE is specified when the file is created, the value specified is the default value used to allocate additional storage for the file. If you specify EXTENDSIZE when you open an existing file, the value you specify supersedes any EXTENDSIZE value specified when the file was created, and remains in effect until you close the file. Unless specifically overridden, the default EXTENDSIZE value is in effect on later openings of the file.

IOSTAT

ios Is an integer scalar memory reference.

If no error exists, ios is defined as zero; if an error exists, ios is defined as a positive integer. IOSTAT applies only to the OPEN statement in which it appears and not to later I/O operations on the logical unit that it opened. However, you can use the IOSTAT parameter in later I/O statements to perform a similar function.

Secondary operating system messages do not display when IOSTAT is specified. To display these messages, remove IOSTAT or use a platform-specific method such as a OpenVMS condition handler. (For more information, see your user manual.)

KEY

kspec Takes the following form:

e1:e2[:dt[:dr]]

e1 Is the position of the first byte of the key in the record. e2 Is the position of the last byte of the key in the record. dt Is the data type of the key: CHARACTER (*DEFAULT*) or INTEGER. dr Is the direction of the key: ASCENDING (*DEFAULT*) or DESCENDING.

The length of the key must not exceed 255 bytes. The first byte position of the key must be at least 1 and the last byte position must not exceed the length of the record.

If the key type is INTEGER, the key length must be either 2 or 4.

Defining Primary and Alternate Keys:

You must define at least one key in an indexed file. This primary key is the default key. It usually has a unique value for each record (no duplicates). Alternate keys can be duplicated.

You can choose to define alternate keys. RMS allows up to 254 alternate keys. However, individual OPEN statements only allow up to 85 key definitions, a number that is further reduced when multiple OPEN statements appear together in a program unit.

If a file requires more keys than the OPEN statement limit, you must create it from another language or with the File Definition Language (FDL).

Specifying and Referencing Keys:

You must specify the KEY parameter when creating an indexed file. However, you do not have to respecify it when opening an existing file because key attributes are permanent aspects of the file. These attributes include key definitions and reference numbers for later I/O operations. If you do choose to specify the KEY parameter for an existing file, your specification must be identical to the established key attributes.

Following I/O operations use a reference number, called the key-of-reference number, to identify a particular key. You do not specify this number; it is determined by the key's position in the specification list: the primary key is key-of-reference number 0; the first alternate key is key-of-reference number 1, and so forth.

MAXREC

mr Is an numeric expression whose value specifies the maximum number of records permitted in a direct access file. The default is the maximum allowed (2**32-1).

NAME

Specifies that records are not to cross disk block boundaries. If a record exceeds the size of a physical block, an error occurs.

ORGANIZATION

org Is a character expression with one of the following values:

'SEQUENTIAL' Records are stored in the order that they are written. Access mode must be sequential, append, or direct (fixed-length records only). (*DEFAULT FOR NEW FILES*)

'RELATIVE' Records are stored in numbered positions. Access mode must be direct or sequential.

'INDEXED' Records are stored according to the values of their keys. Access mode must be indexed or sequential.

The default for an existing file is its current organization.

READONLY

Prohibits write access to the file. Enables users with read access but not write access to access the file.

The Fortran I/O system's default file access privileges are read-write, which can cause run-time I/O errors if the file protection does not permit write access.

The READONLY keyword has no effect on the protection specified for a file. Its main purpose is to allow a file to be read simultaneously by two or more programs. For example, if you wish to open a file to read the file but want to allow others to read the same file while you have it open, specify the READONLY keyword.

RECL

rl Is an numeric expression whose value indicates the length of logical records in a file.

The value of "rl" does not include space for control information, such as for two segment control bytes (if present) or the bytes that RMS requires for maintaining record length and deleted record control information. The specification is for record data only.

The value of "r1" is expressed in units of bytes or longwords, depending on the record's format. Formatted records use byte units and unformatted records use longword units (which are equal to 4 bytes).

The following are the maximum values that can be specified for "r1" for disk files that use the fixed-length record format:

Sequential formatted 32767 bytes Sequential unformatted 8191 longwords Relative formatted 32255 bytes Relative unformatted 8063 longwords Indexed formatted 32224 bytes Indexed unformatted 8056 longwords Tape formatted 9999 bytes Tape unformatted 2499 longwords

For other record formats and device types, the record size limit can be less, as described in the "OpenVMS Record Management Services Reference Manual".

RECL is mandatory when opening new files (STATUS='NEW', 'UNKNOWN, or 'SCRATCH') and when one or more of the following conditions exists:

o The record format is fixed length (RECORDTYPE='FIXED').

o The file organization is relative or indexed (ORGANIZATION='RELATIVE' or 'INDEXED').

o The file is opened for direct access (ACCESS='DIRECT').

RECL is optional in all other cases. Default values for optional cases depend on the value of the RECORDTYPE parameter.

The following are the RECL default values:

RECORDTYPE value RECL value ---------------- -----------------------------------------

'FIXED' None; value must be explicitly specified. All other types 133 bytes (for formatted records) 511 longwords (for unformatted records)

The interpretation and effect of the logical record length varies as follows:

o If the file contains segmented records, RECL specifies the maximum length for any segment (including the two segment-control bytes).

o If the file contains fixed-length records, RECL specifies the size of each record.

o If the file contains variable-length records, RECL specifies the maximum length for any record.

o If your program attempts to write to an existing file a record that is longer than the logical record length, an error occurs.

o If you are opening an existing file that contains fixed-length records or has relative organization and you specify a value for RECL that is different from the actual length of the records in the file, an error occurs.

RECORDSIZE

RECORDSIZE is the nonstandard synonym for RECL.

RECORDTYPE

typ Is a character expression with one of the following values:

'FIXED' All records are one size. Short records are padded with blanks (formatted files) or zeros (unformatted files).

'VARIABLE' Records can vary in length.

'SEGMENTED' A record consists of one or more variable length records, which can exist in different physical blocks. Valid only for unformatted, sequential files with sequential access.

'STREAM' Data is not grouped into records and contains no control information.

'STREAM_CR' Variable-length records whose length is indicated by carriage-returns embedded in the data.

'STREAM_LF' Variable-length records whose length is indicated by line-feeds (new lines) embedded in the data.

When you open a file, default record types are as follows:

+-------------------------------------+---------------------+ | File Type | Default Record Type | +-------------------------------------+---------------------+ | Relative or indexed files | 'FIXED' | | Direct access sequential files | 'FIXED' | | Formatted sequential access files | 'VARIABLE' | | Unformatted sequential access files | 'SEGMENTED' | +-------------------------------------+---------------------+

A segmented record consists of one or more variable-length records. Using segmented records allows a Fortran logical record to span several physical records. Only unformatted sequential access files with sequential organization can use segmented records. You cannot specify <SINGLE_QUOTE>SEGMENTED<SINGLE_QUOTE> for any other file type.

If you do not specify the RECORDTYPE parameter when you are accessing an existing file, the record type of the file is used --- except for unformatted sequential-access files with sequential organization and variable-length records. These files have a default of 'SEGMENTED'.

If you do specify the RECORDTYPE parameter when you are accessing an existing file, the type that you specify must match the type of an existing file.

In fixed-length record files, if an output statement does not specify a full record, the record is filled with spaces in a formatted file and zeros in an unformatted file.

You cannot use an unformatted READ statement to access an unformatted sequential organization file containing variable-length records, unless you specify the corresponding RECORDTYPE value in your OPEN statement.

Files containing segmented records can be accessed only by unformatted sequential Fortran I/O statements.

SHARED

Specifies that the file can be accessed by more than one user at the same time.

STATUS

sta Is a character expression with one of the following values:

'OLD' Open an existing file 'NEW' Create a new file; if the file already exists an error occurs 'SCRATCH' Create a new file and delete it when the file is closed 'UNKNOWN' Open the file as OLD; if it does not exist, then open the file as NEW

The default is 'UNKNOWN'. However, if you implicitly open a file using WRITE, or you specify the /NOF77 compiler option, or OPTIONS /NOF77, the default value is 'NEW'. If you implicitly open a file using READ, the default value is 'OLD'.

Scratch files (STATUS='SCRATCH') are created on the user's default disk (SYS$DISK) and are not placed in a directory or given a name that is externally visible. To specify a different device, use the FILE keyword.

TYPE

u Is a numeric expression that specifies the logical unit to which a file is to be connected.

The unit specification must appear in the parameter list, unless the unit specifier is the first element in the list.

The logical unit may already be connected to a file when an OPEN statement is executed. If this file is not the same as the one to be opened, the OPEN statement executes as if a CLOSE statement had executed just before it.

If the file to be opened is already connected to the unit or if the file specifier (FILE keyword) is not included in the OPEN statement, only the blank specifier (BLANK keyword) can have a value different from the one currently in effect. The position of the file is unaffected.

USEROPEN

p Is the symbolic name of the USEROPEN procedure. The USEROPEN parameter specifies a user-written EXTERNAL function that controls the opening of the file.

The name must be declared EXTERNAL in the program unit with the OPEN statement, and if typed, it must be INTEGER*4.