The File Definition Language facility helps you design data files that can be processed efficiently by using a model file (FDL file) whose attributes (characteristics) are subsequently applied to the data file. This section provides an overview of an FDL file, briefly describing each of its primary attributes. Other sections expand on each of the primary attributes, presenting them in alphabetical order.

An FDL file is a collection of file sections, where each section describes a file attribute. The file sections appear in the following order:

The TITLE, IDENT, AREA, KEY, ANALYSIS_OF_AREA, and ANALYSIS_OF_KEY sections take values. The SYSTEM, FILE, DATE, RECORD, ACCESS, SHARING, and CONNECT sections do not take values; instead, they serve as labels for the related sections. The ANALYSIS_OF_AREA and ANALYSIS_OF_KEY sections appear only in FDL files created with the Analyze/RMS_File utility (ANALYZE/RMS_FILE).

Each section may include a lower order of file characteristics called secondary attributes, and some secondary attributes have a third level of attributes called qualifiers. An FDL file consists of attribute keywords followed by their assigned values. Lowercase letters and uppercase letters are equivalent and can be used interchangeably. Secondary attributes can be either create-time attributes or run-time attributes. Create-time attribute values are established when the file is created. Run-time attributes are established just prior to an application's opening or connecting to an existing file by calling the FDL$PARSE routine and by passing the routine the applicable FDL file specification. See the VSI OpenVMS Utility Routines Manual for details about using the FDL$PARSE routine.

Attributes take one of the following value types:

The following sections describe primary and secondary attributes and contain cross-references to corresponding fields (parameters) in RMS control blocks. The term DECnet for OpenVMS operations refers to remote file access between two OpenVMS operating systems and, unless stated otherwise, attributes are supported for DECnet for OpenVMS operations.

The ACCESS primary attribute allows you to specify file-processing operations by assigning appropriate values to the secondary attributes. The ACCESS keyword takes no values; it serves only to define this section.

The following table lists the ACCESS secondary attributes and their default values. Note that all of the ACCESS secondary attributes are run-time attributes.

BLOCK_IO

This switch specifies block I/O operations involving either the Read or the Write RMS service, depending on whether you have specified the GET (Read service) or the PUT (Write service) ACCESS secondary attributes. If you specify BLOCK_IO, no record I/O operations (such as DELETE, GET, PUT, TRUNCATE, or UPDATE) can be performed. The BLOCK_IO secondary attribute also permits you to use the Space service.

The BLOCK_IO attribute corresponds to the BIO option in the FAB$B_FAC field.

DELETE

This switch enables Delete operations. The DELETE attribute corresponds to the DEL option in the FAB$B_FAC field.

GET

If you also specify the BLOCK_IO attribute, you can perform Read services. The GET attribute corresponds to the GET option in the FAB$B_FAC field.

PUT

This switch specifies the Put service or the Extend service. PUT is the default when you create a file. If you specify the PUT attribute and the BLOCK_IO attribute, you can perform Write services.

The PUT attribute corresponds to the PUT option in the FAB$B_FAC field.

RECORD_IO

This switch allows mixed record I/O and block I/O operations under certain circumstances (see the VSI OpenVMS Record Management Services Reference Manual for more information).

The RECORD_IO attribute corresponds to the BRO option in the FAB$B_FAC field.

TRUNCATE

This switch allows Truncate operations. The TRUNCATE attribute corresponds to the TRN option in the FAB$B_FAC field.

UPDATE

This switch selects either the Update service or the Extend service. The UPDATE attribute corresponds to the UPD option in the FAB$B_FAC field.

ANALYZE/RMS_FILE creates the ANALYSIS_OF_KEY section and supplies appropriate values. The Edit/FDL utility uses the ANALYSIS_OF_KEY section in its Optimize script for FDL files that define an indexed file.

The primary attribute ANALYSIS_OF_KEY has a numeric value that represents the key being analyzed (0 is the primary key).

DATA_FILL

This attribute shows the percentage of bytes per bucket in the data level that has been filled.

DATA_KEY_COMPRESSION

This attribute shows the percentage of compression achieved for the primary keys. For example, if the keys added up to 1000 bytes and compression reduced that figure to 600 bytes, the value shown in the DATA_KEY_COMPRESSION attribute would be 40 (representing 40 percent compression).

Negative compression might occur because of the overhead involved. If you see a negative value, you should disable that type of compression in the KEY section.

DATA_RECORD_COMPRESSION

This attribute shows the percentage of compression that has occurred in the level 0 data record. For example, if compression reduces the number of bytes in the data records added from 100,000 to 70,000, the value shown in the DATA_RECORD_COMPRESSION attribute would be 30 (representing 30 percent compression).

Negative compression might occur because of the overhead involved. If you see a negative value, you should disable that type of compression in the KEY section.

This attribute applies only to the primary key.

DATA_RECORD_COUNT

This attribute shows the number of data records in the file.

DATA_SPACE_OCCUPIED

This attribute shows the size, in blocks, of the level 0 of the index structure.

DEPTH

This attribute shows the number of index levels in the index structure. The value does not include the data level.

DUPLICATES_PER_SIDR

This attribute shows the average number of duplicate key values for the secondary index data records (SIDR); that is, the value is the total number of duplicates divided by the total number of SIDRs.

This attribute applies only to alternate keys.

INDEX_COMPRESSION

This attribute shows the percentage of compression that has occurred in the index records within the index levels. If the full indexes amounted to 10,000 bytes and compression reduced this value to 8000 bytes, the value shown in the INDEX_COMPRESSION attribute would be 20 (representing 20 percent).

INDEX_FILL

This attribute shows the percentage of bytes per bucket that have been filled in the index levels.

INDEX_SPACE_OCCUPIED

This attribute shows the size, in blocks, of the index levels (level 1 and greater).

LEVEL1_RECORD_COUNT

This attribute indicates the number of records in the level 1 index, which is the index level immediately above the data. When duplicate key values (for SIDRs) have been specified, even when SIDR overflow buckets exist, the tuning algorithm of EDIT/FDL is made more accurate.

Generally, every bucket on level 0 of an alternate key has a pointer record from level 1 of the alternate key. However, there are no pointers from level 1 to any overflow buckets. LEVEL1_RECORD_COUNT keeps track of how many records are in level 1, particularly when duplicate key values force overflow buckets to be created.

MEAN_DATA_LENGTH

This attribute shows the average length, in bytes, of the data records. This does not take compression into account.

MEAN_INDEX_LENGTH

This attribute shows the average length, in bytes, of the index records. This does not take compression into account.

The AREA section is an RMS-specific region of an indexed file that you cannot create or manipulate from a high-level programming language. RMS provides appropriate areas for you when you create an indexed file.

If you want to create or manipulate areas in an indexed file, you must include the AREA primary attribute in an FDL file. The AREA primary attribute acts as a header for a section in the FDL file that describes areas. It takes a numeric value in the range 0 to 254 that identifies the area. To define multiple areas for an indexed file, you must specify a separate AREA section for each area.

Most AREA secondary attributes (except for the EXACT_POSITIONING, POSITION, and VOLUME secondary attributes) have corresponding FILE secondary attributes. The values you specify for AREA secondary attributes override values you specify for corresponding secondary attributes in the FILE section.

The AREA primary attribute corresponds to the XAB$B_AID field in a XAB (extended attribute block).

ALLOCATION

This numeric attribute establishes the initial number of blocks allocated to an area. Its value must be an integer in the range 0 to 4,294,967,295. If you take the default value of 0, the system allocates no space for the area.

The ALLOCATION attribute corresponds to the XAB$L_ALQ field in a XAB.

ASYNCHRONOUS

This switch specifies that the task is to be done asynchronously. This option is relevant only to file tasks that involve I/O operations. It is typically used with success/error ASTs, or in conjunction with the $WAIT service, to synchronize the program with task completion.

The ASYNCHRONOUS attribute corresponds to the FAB$V_ASY bit in the FAB$L_FOP field.

BEST_TRY_CONTIGUOUS

This switch controls whether an area is allocated contiguous space, assuming there is enough space for it. If you set the switch to YES and there is not enough space, the area is allocated noncontiguously.

If you take the default, NO, this attribute has no effect.

The BEST_TRY_CONTIGUOUS attribute corresponds to the CBT option in the XAB$B_AOP field.

BUCKET_SIZE

This numeric attribute establishes the number of blocks per bucket for this area. Its value must be an integer in the range 0 to 63. If you take the default value of 0, RMS calculates the smallest bucket size capable of holding the largest record. If RMS–11 is to process the file, the bucket size is limited to 32 blocks.

The BUCKET_SIZE attribute corresponds to the XAB$B_BKZ field.

CONTIGUOUS

This switch controls whether RMS allocates contiguous space for the file. If there is not enough contiguous space, RMS returns an error when you try to create the file.

When you take the default, NO, FDL ignores this attribute.

The CONTIGUOUS attribute corresponds to the CTG option in the XAB$B_AOP field.

EXACT_POSITIONING

This switch mandates that the area is allocated the precise location you specify with either the POSITION CYLINDER attribute or the POSITION LOGICAL attribute. If the location is not available, RMS returns an error. When you take the default (NO), RMS allocates the area nearest the specified location.

The EXACT_POSITIONING attribute corresponds to the HRD option in the XAB$B_AOP field.

EXTENSION

This numeric attribute establishes the area's default extension size, in blocks. The extension is the space added to the area when the allocated space is filled.

This value must be an integer in the range 0 to 65,535. If you take the default (0), the system determines the extension size.

The EXTENSION attribute corresponds to the XAB$W_DEQ field.

POSITION

(FID-num,FID-seq,RVN)

The POSITION attribute corresponds to the XAB$B_ALN, XAB$L_LOC, and XAB$W_RFI fields in a XAB. This attribute is not supported for DECnet for OpenVMS operations; use the keyword NONE.

VOLUME

This attribute specifies the area location by using the relative volume number in a Files-11 disk volume set.

You must specify an integer in the range 0 to 255. If you take the default, 0, it means that you do not want to control the area's placement on the volume set.

The VOLUME attribute corresponds to the XAB$W_VOL field.

ASYNCHRONOUS

This switch specifies asynchronous I/O operations. When you select this attribute, RMS returns control to your program as soon as an I/O operation begins. The switch is ignored for process-permanent files.

The ASYNCHRONOUS attribute corresponds to the ASY option in the RAB$L_ROP field.

BLOCK_IO

This switch determines whether block or record I/O operations are performed. If you set the switch to YES, only block operations are permitted. If you set the switch to NO, only record operations are allowed for relative and indexed files. However, if you specify the ACCESS section RECORD_IO attribute, mixed block and record operations may be performed on sequential files only.

The BLOCK_IO attribute corresponds to the BIO option in the RAB$L_ROP field.

BUCKET_IO

This numeric attribute specifies a relative record number or a numeric value representing the virtual block number to be accessed. You use this attribute with records in a relative file or when you want block I/O to be performed.

The BUCKET_IO attribute corresponds to the RAB$L_BKT field.

CONTEXT

You can use this attribute to specify any numeric value, up to 4 bytes in length. RMS does not use the CONTEXT attribute; it is provided exclusively for your use. For example, you could use it to communicate with a completion routine in your program.

The CONTEXT attribute corresponds to the RAB$L_CTX field.

END_OF_FILE

This switch directs RMS to connect to the end of the file.

The END_OF_FILE attribute corresponds to the EOF option in the RAB$L_ROP field.

FAST_DELETE

This switch directs RMS not to delete the alternate index pointers used for duplicate records when you delete a record. Instead, RMS deletes the pointers and generates an appropriate error message only when you subsequently attempt to access the deleted record. The FAST_DELETE attribute avoids the overhead usually involved with RMS record deletions—updating the data level, the primary index, and then the alternate indexes.

The FAST_DELETE attribute corresponds to the FDL option in the RAB$L_ROP field.

FILL_BUCKETS

This switch directs RMS to load buckets according to the fill size established at file-creation time. If you do not set the switch, RMS ignores the established bucket fill size and fills buckets completely.

The FILL_BUCKET attribute corresponds to the LOA option in the RAB$L_ROP field.

KEY_GREATER_EQUAL

When using an ascending data type, this switch directs RMS to access the first record in an indexed file containing a key of reference value greater than or equal to the value described by the RAB$L_KBF and RAB$B_KSZ fields. For a descending data type, RMS accesses the first record that contains a key of reference value less than or equal to the value described by the RAB$L_KBF and RAB$B_KSZ fields.

If you set neither this switch nor the KEY_GREATER_THAN switch, RMS accesses the first record that contains a key of reference value equal to the value described by the RAB$L_KBF and RAB$B_KSZ fields.

This attribute corresponds to the KGE option in the RAB$L_ROP field. For more information about the RAB$L_KBF and RAB$B_KSZ fields, refer to the VSI OpenVMS Record Management Services Reference Manual.

KEY_GREATER_THAN

When using an ascending data type, this switch directs RMS to access the first record in an indexed file containing a key of reference value greater than the value described by the RAB$L_KBF and RAB$B_KSZ fields. When using a descending data type, the switch directs RMS to access the first record that contains a key of reference value less than that specified in the RAB$L_KBF and RAB$B_KSZ fields.

If you set neither this switch nor the KEY_GREATER_EQUAL switch, RMS accesses the first record that contains a key of reference value equal to the value described by the RAB$L_KBF and RAB$B_KSZ fields.

The KEY_GREATER_THAN attribute corresponds to the KGT option in the RAB$L_ROP field. For more information about the RAB$L_KBF and RAB$B_KSZ fields, refer to the VSI OpenVMS Record Management Services Reference Manual.

KEY_LIMIT

This switch directs RMS to compare the key value described by the RAB$L_KBF and RAB$B_KSZ fields to the value in the record accessed in sequential mode. If you set this switch and the record's key value is greater than the limit key value, RMS returns the RMS$_OK_LIM status code.

This attribute corresponds to the LIM option in the RAB$L_ROP field.

KEY_OF_REFERENCE

This numeric attribute specifies the key or index (such as primary, or first alternate) by which you want to process records in a file. The default value, 0, indicates the primary key. Values 1 to 254 indicate alternate keys.

The KEY_OF_REFERENCE attribute applies only to indexed files and it corresponds to the RAB$B_KRF field.

LOCATE_MODE

This switch directs RMS to return records by supplying a pointer to the data rather than by copying the data to the user buffer.

The LOCATE_MODE attribute corresponds to the LOC option in the RAB$L_ROP field.

LOCK_ON_READ

This switch permits a process reading a record to prohibit other processes from modifying the record.

The LOCK_ON_WRITE attribute takes precedence over the LOCK_ON_READ attribute, and the NOLOCK attribute takes precedence over both.

The LOCK_ON_READ attribute corresponds to the REA option in the RAB$L_ROP field.

LOCK_ON_WRITE

This switch permits a process to allow other processes to read a record that it is modifying.

The LOCK_ON_WRITE attribute takes precedence over the LOCK_ON_READ attribute, and the NOLOCK attribute takes precedence over both.

The LOCK_ON_WRITE attribute corresponds to the RLK option in the RAB$L_ROP field.

MANUAL_UNLOCKING

This switch prohibits RMS from unlocking records automatically. Instead, after a record is locked by a Get, Find, or Put operation, RMS must use a Free or Release operation to explicitly unlock the record.

The NOLOCK attribute takes precedence over the MANUAL_UNLOCKING attribute and corresponds to the ULK option in the RAB$L_ROP field.

MULTIBLOCK_COUNT

This numeric attribute permits a process that is accessing a sequential disk file to specify the number of blocks, in the range 0 to 127, allocated to each I/O buffer.

The MULTIBLOCK_COUNT attribute optimizes data throughput for sequential operations, and it does not affect the structure of the file. It reduces the number of times you have to access the disk for record operations, thereby reducing execution time. However, the extra buffering increases memory requirements.

If you do not specify this attribute or if you specify the value 0, RMS uses the process default for the multiblock count. If the process default is 0, RMS uses the system default. If the system default is 0, the default size for each I/O buffer is one block. Use the DCL command SET RMS_DEFAULT to establish process or system defaults.

The MULTIBLOCK_COUNT attribute corresponds to the RAB$B_MBC field and is not supported for DECnet for OpenVMS operations.

MULTIBUFFER_COUNT

This numeric attribute specifies the number of buffers, in the range 0 to 127, to be allocated at connect time.

If you do not select this attribute or if you use the value 0, RMS uses the process default for the particular file organization and device type. If the process default is 0, the system default for the particular file organization and device type applies.

If the system default is likewise 0, one buffer is allocated. However, if you specify either the READ_AHEAD attribute or the WRITE_BEHIND attribute, RMS allocates at least two buffers. Similarly, RMS allocates a minimum of two buffers for an indexed sequential file or for a process-permanent file.

The MULTIBUFFER_COUNT attribute corresponds to the RAB$B_MBF field and is not supported for DECnet for OpenVMS operations.

NOLOCK

This switch specifies that the record accessed through a Get or Find operation is not to be locked. The NOLOCK attribute takes precedence over all other attributes that control record locking, such as MANUAL_UNLOCKING, LOCK_ON_READ, and LOCK_ON_WRITE.

The NOLOCK attribute corresponds to the NLK option in the RAB$L_ROP field.

NONEXISTENT_RECORD

This switch specifies that if a record randomly accessed with a Get or Find RMS operation does not exist (was never inserted into the file or was deleted), it is to be processed anyway, locking the record cell if necessary.

The NONEXISTENT_RECORD attribute does not apply to indexed files, and it corresponds to the NXR option in the RAB$L_ROP field.

READ_AHEAD

This switch is used with multiple buffers (see MULTIBUFFER_COUNT) to indicate read-ahead operations. It directs the system not to wait for I/O completion because input and computing can overlap. That is, when one buffer is filled, the next record is read into a second buffer while I/O operations take place in the first buffer.

If you specify READ_AHEAD when the multibuffer count is 0, two buffers are allocated to allow multibuffering. If you specify two or more buffers, multibuffering is allowed regardless. However, if you specify a buffer count of 1, multibuffering is disabled.

The READ_AHEAD attribute applies only to sequential file processing and is ignored for unit record device I/O. This attribute corresponds to the RAH option in the RAB$L_ROP field and is not supported for DECnet for OpenVMS operations.

READ_REGARDLESS

This switch permits you to read a record even if it is locked, allowing some control over access. If a record is locked against all access and you request a Find or Get RMS operation, RMS returns the record anyway.

The READ_REGARDLESS attribute corresponds to the RRL option in the RAB$L_ROP field.

TIMEOUT_ENABLE

This numeric attribute specifies the maximum time value, in seconds, allowed for a record input wait caused by a locked record when you specify the WAIT_FOR_RECORD attribute. This attribute also applies to the time allowed for a character to be received during terminal input. If the timeout period expires, RMS returns an error status.

The TIMEOUT_ENABLE attribute also serves a special purpose for mailbox devices. If you specify this attribute with a TIMEOUT_PERIOD of 0, Get and Put RMS operations to mailbox devices use the IO$M_NOW modifier. The operation then completes immediately instead of synchronizing with another cooperating writer or reader of the mailbox. See the VSI OpenVMS I/O User's Reference Manual for a further discussion of mailboxes.

The TIMEOUT_ENABLE attribute corresponds to the TMO option in the RAB$L_ROP field and is not supported for DECnet for OpenVMS operations.

TIMEOUT_PERIOD

This numeric attribute specifies the maximum duration, in seconds (0 to 255), of a Get operation. If the user specifies a Get operation from the terminal and the attribute value is 0, RMS does not return the current contents of the type-ahead buffer.

You can use this attribute only with the TIMEOUT_ENABLE attribute. It corresponds to the RAB$B_TMO field and is not supported for DECnet for OpenVMS operations.

TRUNCATE_ON_PUT

This switch permits a Put or Write operation at any point in a file, truncating the file at that point. A Write operation causes the end-of-file (EOF) mark to immediately follow the last byte written.

TRUNCATE_ON_PUT can only be used with sequential files. It corresponds to the TPT option in the RAB$L_ROP field.

TT_CANCEL_CONTROL_O

This switch ensures that terminal output is not discarded if you press Ctrl/O. It corresponds to the CCO option in the RAB$L_ROP field and is not supported for DECnet for OpenVMS operations.

TT_PROMPT

This switch specifies that the contents of the prompt buffer be used as a prompt on a terminal-read operation.

It corresponds to the PMT option in the RAB$L_ROP field and is not supported for DECnet for OpenVMS operations.

TT_PURGE_TYPE_AHEAD

This switch eliminates any information that might be in the type-ahead buffer on a terminal-read operation. The TT_PURGE_TYPE_AHEAD attribute corresponds to the PTA option in the RAB$L_ROP field and is not supported for DECnet for OpenVMS operations.

()TT_READ_NOECHO

This switch specifies that input data is not to be echoed (displayed) on the terminal as it is entered on the keyboard. The TT_READ_NOECHO attribute corresponds to the RNE option in the RAB$L_ROP field and is not supported for DECnet for OpenVMS operations.

TT_READ_NOFILTER

This switch specifies that the Ctrl/U, Ctrl/R, and Delete keys are not to be considered control commands from the terminal but are to be passed to the user program.

The TT_READ_NOFILTER attribute corresponds to the RNF option in the RAB$L_ROP field and is not supported for DECnet for OpenVMS operations.

TT_UPCASE_INPUT

This switch changes lowercase characters read from a terminal to uppercase. The TT_UPCASE_INPUT attribute corresponds to the CVT option in the RAB$L_ROP field and is not supported for DECnet for OpenVMS operations.

UPDATE_IF

This switch specifies that a Put operation for a record that already exists is converted to an Update operation. This attribute is necessary to overwrite (as opposed to update) an existing record in relative and indexed sequential files.

Indexed files using UPDATE_IF must not allow duplicates on the primary key.

The UPDATE_IF attribute corresponds to the UIF option in the RAB$L_ROP field.

WAIT_FOR_RECORD

This switch directs RMS to wait for a currently locked record until it becomes available. You can use this attribute with the TIMEOUT_ENABLE and TIMEOUT_PERIOD attributes to limit waiting periods to a specified time.

The WAIT_FOR_RECORD attribute corresponds to the WAT option in the RAB$L_ROP field.

WRITE_BEHIND

This switch is used with multiple buffers (see MULTIBUFFER_COUNT) to specify write-behind operations. It directs the system not to wait for I/O completion because computing and output can overlap. When one buffer is filled, the next record is written into a second buffer while the I/O operation takes place for the first buffer.

If you specify WRITE_BEHIND when the multibuffer count is 0, two buffers are allocated to allow multibuffering. If you specify two or more buffers, multibuffering is allowed regardless. However, if you specify a buffer count of 1, multibuffering is disabled.

The WRITE_BEHIND attribute applies to sequential file processing only and is ignored for unit record device I/O. This attribute is not supported for DECnet for OpenVMS operations.

This attribute corresponds to the WBH option in the RAB$L_ROP field.

In general, you should let the system specify values for the DATE secondary attributes. The only secondary attribute you can routinely specify is EXPIRATION.

BACKUP

dd-mmm-yyyy hh:mm:ss.cc.

The BACKUP attribute corresponds to the XAB$Q_BDT field.

CREATION

dd-mmm-yyyy hh:mm:ss.cc.

The CREATION attribute corresponds to the XAB$Q_CDT field.

EXPIRATION

dd-mmm-yyyy hh:mm:ss:cc.

The EXPIRATION attribute corresponds to the XAB$Q_EDT field.

REVISION

dd-mmm-yyyy hh:mm:ss.cc.

The REVISION attribute corresponds to the XAB$Q_RDT field.

The FILE section allows you to specify file processing and file-related characteristics for your file. The FILE keyword takes no values; it serves only to define this section.

FILE section attributes (ALLOCATION, BEST_TRY_CONTIGUOUS, BUCKET_SIZE, CONTIGUOUS, and EXTENSION) have corresponding AREA section attributes. Values you specify for these attributes in the AREA section override associated values that you specify in the FILE section.

ALLOCATION

This numeric attribute establishes the number initially allocated to the file. The value must be an integer in the range 0 to 4,294,967,295. If you take the default (0), the system allocates no initial space for the file.

The ALLOCATION attribute corresponds to the FAB$L_ALQ field.

ASYNCHRONOUS

This switch specifies asynchronous I/O operations. When you select this attribute, RMS returns control to your program as soon as an I/O operation begins. The switch is ignored for process-permanent files.

The ASYNCHRONOUS attribute corresponds to the ASY option in the RAB$L_ROP field.

BEST_TRY_CONTIGUOUS

This switch controls whether the file is to be allocated contiguously, assuming there is sufficient contiguous space for it. If you set the switch and there is not enough space, the system allocates the file noncontiguous space. If you take the default, no space is allocated.

The BEST_TRY_CONTIGUOUS attribute corresponds to the CBT option in the FAB$L_FOP field.

BUCKET_SIZE

This numeric attribute establishes the number of blocks per bucket. Its value must be an integer in the range 0 to 63. If you take the default (0), RMS computes the smallest bucket size capable of holding the largest record. Files processed by RMS–11 are limited to 32 blocks.

If you specify separate areas for the data level and the index levels, you must define separate bucket sizes for each file area; thus, the corresponding attribute in each AREA section overrides this related attribute in the FILE section.

The BUCKET_SIZE attribute corresponds to the FAB$B_BKS field.

CLUSTER_SIZE

This numeric attribute specifies the number of blocks allocated to a disk cluster. The disk cluster size can be established only when a disk volume is initialized.

The CLUSTER_SIZE attribute is output from the Analyze/RMS_File utility (ANALYZE/RMS_FILE), which returns the actual value of the disk cluster size to EDIT/FDL for use during an Optimize script.

CONTEXT

This numeric attribute contains a user-specified value 4 bytes long. RMS never uses the attribute for record management activities. It is intended solely for you to convey user information to a completion routine in your program.

The CONTEXT attribute corresponds to the FAB$L_CTX field.

CONTIGUOUS

This switch specifies that a file is allocated contiguous space.

If there is not enough contiguous space for the file's initial allocation, RMS returns an error.

If you take the default, the system allocates no space for the file.

This attribute corresponds to the CTG option in the FAB$L_FOP field.

CREATE_IF

This switch creates a file if the specified file does not already exist and, where applicable, RMS returns the alternate success status RMS$_CREATED to indicate that the file was created, not just opened. If the file exists, RMS opens it.

The CREATE_IF attribute is valid as input to the Create service only. It overrides the SUPERSEDE (supersede existing file) attribute and corresponds to the CIF option in the FAB$L_FOP field.

DEFAULT_NAME

This attribute takes a string value that defines portions of the file specification for the data file being created.

When a utility creates a data file from an FDL file, it first attempts to get the file specification from the calling process. If the call includes a full file specification, the utility ignores the DEFAULT_NAME and NAME attributes.

When a process supplies a partial file specification, the invoked utility tries to complete the file specification from the DEFAULT_NAME string. If the calling process does not specify a value for DEFAULT_NAME, the utility uses the RMS defaults.

If the calling process supplies a file specification by using the NAME attribute, the utility uses it. If the NAME attribute includes only a partial file specification, the utility uses it and examines the DEFAULT_NAME attribute for the rest of the file specification.

If the NAME and DEFAULT_NAME attributes together provide only a partial file specification, the utility uses RMS default values to complete the file specification.

For example, if you assign the value WRKD$:.KSM to DEFAULT_NAME, unless you specify otherwise, the created data file specification takes the device name WRKD$ and the file type .KSM.

The NAME and DEFAULT_NAME attributes correspond to the FAB$L_DNA and the FAB$B_DNS fields, respectively.

DEFERRED_WRITE

This switch specifies that the writing of modified I/O buffers to the file is deferred until that buffer is needed for other purposes. This attribute applies only to relative files, indexed files, and sequential files opened for shared access.

The DEFERRED_WRITE attribute corresponds to the DFW option in the FAB$L_FOP field. This attribute is not supported for DECnet for OpenVMS operations.

DELETE_ON_CLOSE

This switch specifies that the file is to be deleted after it is closed. If you select this attribute, you cannot create the file with either the Create/FDL utility or the FDL$CREATE routine because both open and then close the file. Therefore, the file will not exist long enough to be used. To create a file with the DELETE_ON_CLOSE attribute, you must use the FDL$PARSE routine.

The DELETE_ON_CLOSE attribute corresponds to the DLT option in the FAB$L_FOP field. The default is to ignore this attribute.

DIRECTORY_ENTRY

This switch specifies a temporary file created and retained with a directory entry. When you set this switch to NO, RMS retains the file but does not include it as a directory entry. To access the file, you must use its file identification number (FID).

The DIRECTORY_ENTRY attribute corresponds to the TMP option in the FAB$L_FOP field.

EXTENSION

This numeric attribute establishes the size, in blocks, of the file's default extension value. Each time the file is automatically extended, the specified number of blocks is added. The value for this attribute must be an integer in the range 0 to 65,535. When you take the default (0), the system determines the extension size.

The EXTENSION attribute corresponds to the FAB$W_DEQ field.

FILE_MONITORING

This switch enables RMS performance monitoring. It corresponds to the XABITM field XAB$_STAT_ENABLE and its default value is NO. Enabling this option applies an application ACE to the specified file. The ACE does not affect access control and is only meaningful to the application assigning it.

GLOBAL_BUFFER_COUNT

This numeric attribute specifies the number of global buffers allocated to the file. The value must be a number in the range 0 to 32,767; the default value is 0.

The GLOBAL_BUFFER_COUNT attribute corresponds to the FAB$W_GBC field. This attribute is not supported for DECnet for OpenVMS operations.

MAX_RECORD_NUMBER

This numeric attribute specifies the maximum number of records that can be placed in a relative file. The value must be an integer in the range 0 to 2,147,483,647. When you take the default value (0), you can place as many records as you want in the relative file, up to the maximum 2,147,483,647.

The MAX_RECORD_NUMBER attribute corresponds to the FAB$L_MRN field.

MAXIMIZE_VERSION

This switch specifies the file's version number. If you take the default, YES, the File Definition Language facility assigns the greater of two possible version numbers: either the number that was part of the file specification or a version number that is 1 higher than the highest existing version number.

When you set the switch to NO, assigning an explicit version number lower than an existing version results in creating a new data file with the lower version number. If you assign an explicit version number that matches an existing version, RMS returns an error.

The MAXIMUM_VERSION attribute corresponds to the MXV option in the FAB$L_FOP field.

MT_BLOCK_SIZE

This numeric attribute establishes the number of bytes in a magnetic tape file block. The value can be 0, an integer in the range 20 to 65,535 for ANSI-formatted tapes, or an integer in the range 14 to 65,532 for foreign tapes (tapes that are not in the standard ANSI format used by OpenVMS operating systems and that must be mounted by means of the DCL command MOUNT/FOREIGN). If you take the default value (0), RMS assigns the block size specified when the tape was mounted.

The MT_BLOCK_SIZE attribute corresponds to the FAB$W_BLS field.

MT_CLOSE_REWIND

This switch controls whether a magnetic tape volume is rewound when the file is closed. The magnetic tape volume does not rewind if you take the default (NO).

The MT_CLOSE_REWIND attribute corresponds to the RWC option in the FAB$L_FOP field.

MT_CURRENT_POSITION

This switch directs RMS to position the magnetic tape volume set immediately after the most recently closed file when it creates the next file. If you use this option when you invoke the $CREATE service, RMS overwrites all files located beyond the current tape position.

If you do not specify either of the position specifiers (MT_CURRENT_POSITION or MT_OPEN_REWIND), RMS creates the new file at the logical end of the tape. If you specify both position specifiers, the MT_OPEN_REWIND attribute overrides the MT_CURRENT_POSITION attribute.

The MT_CURRENT_POSITION attribute corresponds to the POS option in the FAB$B_FOP field.

MT_NOT_EOF

This switch prevents positioning the tape to the end of a file being opened with the PUT attribute specified.

This attribute corresponds to the NEF option in the FAB$L_FOP field.

MT_OPEN_REWIND

This switch specifies that the magnetic tape volume is to be rewound before the file is opened or created. If you use this option to create a tape file, RMS assumes that write operations are to take place at the beginning of the tape, rewinds the tape to the beginning, and proceeds to overwrite the tape data beginning with the first tape file.

Conversely, if you specify this attribute when you open an existing tape file, RMS rewinds to the beginning of the tape but then proceeds to find the specified file before doing any file operations.

Typically, a user specifies the MT_OPEN_REWIND option to improve efficiency in opening a tape file or to ensure access to the correct file when the tape contains files with duplicate names. ANSI tapes allow named files, but they have no directories and can contain repeated instances of files with the same name.

In the first case, assume the tape has 50 files, is positioned at the fortieth file, and the user wants to access the thirtieth file. If the user specifies MT_OPEN_REWIND to the Open service, RMS rewinds the tape to the first file and then winds the tape forward to the thirtieth file. If the user does not specify MT_OPEN_REWIND, RMS winds the tape forward to the end of the tape. Then, not having found the file, RMS rewinds the tape to the first file and proceeds to wind the tape forward to the thirtieth file.

In the second case, assume a tape has two files named X.DAT and is positioned between the two files. Assume further that the user wants to access the first file named X.DAT. If the user does not specify MT_OPEN_REWIND, RMS winds forward until it finds the second file and opens it, instead of opening the desired file. Conversely, if the user does specify MT_OPEN_REWIND, RMS rewinds the tape and then winds forward until it finds and opens the first file named X.DAT.

The MT_OPEN_REWIND option takes precedence over the MT_CURRENT_POSITION option and corresponds to the RWO option in the FAB$L_FOP field.

MT_PROTECTION

This single-character string attribute allows you to control access to a magnetic tape file. The default value is a space character that specifies access is not controlled. If the attribute is a non-space character, you can access the file only by specifying the /OVERRIDE=ACCESSIBILITY qualifier and option when you initialize or mount the volume.

This attribute corresponds to the XAB$B_MTACC field and is not supported for DECnet for OpenVMS operations.

NAME

This string attribute specifies the name of the data file to be created from this FDL file. If you supply a name for the data file, that name overrides the one specified here.

This attribute corresponds to the FAB$L_FNA and the FAB$B_FNS fields.

On Alpha systems, if you have implemented the on-disk-structure level 5 (ODS-5) volume structure of extended file specifications, you can name a file using the 8-bit ISO Latin-1 or 16-bit Unicode (UCS-2) character sets. You can also have a file name exceed the traditional 39.39 character limit to a maximum of 255 characters.

NON_FILE_STRUCTURED

This switch directs that the volume is to be processed in a manner that is not file structured. This attribute corresponds to the NFS option in the FAB$L_FOP field and is not supported for DECnet for OpenVMS operations.

ORGANIZATION

The default is SEQUENTIAL.

This attribute corresponds to the FAB$B_ORG field.

OUTPUT_FILE_PARSE

This switch specifies that the resultant file specification string, if used, is to provide directory, file name, and file type defaults only.

This attribute corresponds to the OFP option in the FAB$L_FOP field.

OWNER

 octal-group-number,octal-user-number

For example, OWNER [12,322] indicates that the person in group 12 with the user number 322 is the owner of the data file.

This attribute corresponds to the XAB$W_GRP and the XAB$W_MBM fields.

PRINT_ON_CLOSE

This switch controls whether the data file is to be spooled to the process default print queue when the file is closed, and applies to sequential files only. When you set the switch to YES, the data file is to be spooled to the process default print queue (SYS$PRINT) after the file is closed.

If you also set DELETE_ON_CLOSE to YES, the file is deleted after it is printed.

This attribute corresponds to the SPL option in the FAB$L_FOP field.

PROTECTION

This keyword attribute specifies file protection by defining the type of file access allowed for each of the four user classes:

You define the access level for each user class by entering the appropriate access-level code as the argument for each user-class keyword. There are four access levels and you can assign one or more to each user class:

Each user class has a unique first letter (S, O, G, and W) and the same is true for each access level (R, W, E, and D). This lets you truncate the code for each user class if you prefer. Note that you must truncate the access level to the leading letter.

(SYSTEM=code,OWNER=code,GROUP=code,WORLD=code)

(SYSTEM:code,OWNER:code,GROUP:code,WORLD:code)

You must enclose the protection specification in parentheses and you have the option of using either the equal sign (=) or a colon (:) to separate each keyword from its associated code value.

By default, RMS assigns the file the default protection for the current process. To see the default protection for the current process, use the DCL command SHOW PROTECTION.

(System=RWED,Owner=RWED,Group=R)

This attribute corresponds to the XAB$W_PRO field.

READ_CHECK

This switch determines whether transfers from disk volumes are followed by read-compare operations.

When you activate the switch, transfers from disk volumes are followed by read-compare operations. This double check increases the likelihood that the system will catch data errors; however, it also increases disk overhead.

Activating this switch does not permanently mark the file for READ_CHECK; it merely selects a run-time option. To permanently mark the file for READ_CHECK, use the SET FILE/DATA_CHECK=READ command.

This attribute corresponds to the RCK option in the FAB$L_FOP field.

REVISION

This numeric attribute specifies the revision number of the data file as an integer in the range 0 to 65,535. Unless you want to change the revision number to some specific number, you should leave this value at its default of 0. When REVISION is set to 0, the file's revision number is incremented each time the file is opened for write access.

This attribute corresponds to the XAB$W_RVN field.

SEQUENTIAL_ONLY

This switch limits the file to sequential processing and related processing options. Any attempt at random access results in an error.

For DECnet for OpenVMS operations, this attribute enables file transfer mode, which is a data access protocol (DAP) feature that allows several records to be transferred in a single network operation. It maximizes throughput for single-direction, sequential-access file transfer.

This attribute corresponds to the SQO option in the FAB$L_FOP field.

STORED_SEMANTICS

Where applicable, this string attribute identifies the file semantics established when a file is created. The string is limited to 64 characters and the attribute corresponds to the XAB$_STORED_SEMANTICS field.

SUBMIT_ON_CLOSE

This switch submits the data file to the process default batch queue (SYS$BATCH) when the file is closed and is appropriate only for sequential command files.

If you also set DELETE_ON_CLOSE to YES, the file is deleted after the batch job completes.

This attribute corresponds to the SCF option in the FAB$L_FOP field and is not supported for DECnet for OpenVMS operations.

SUPERSEDE

This switch replaces the existing data file with a different file of the same name, type, and version.

If you successfully create a new file with the same name, type, and version as an existing file, the old file is deleted.

SUPERSEDE is overridden by the CREATE_IF attribute.

This attribute corresponds to the SCF option in the FAB$L_FOP field.

TEMPORARY

This creates a temporary file that is deleted when it is closed. No directory entry is created for a temporary file.

You cannot create a file that has this attribute by using the CREATE/FDL command or the FDL$CREATE routine, because these commands open and then close the data file before it can be used. You can only use the FDL$PARSE routine to create a file that has the TEMPORARY attribute.

This attribute corresponds to the TMD option in the FAB$L_FOP field.

TRUNCATE_ON_CLOSE

This switch deallocates unused space at the end of a sequential file when the file is closed.

This attribute corresponds to the TEF option in the FAB$L_FOP field.

USER_FILE_OPEN

This switch limits RMS operations to opening or creating a file. If you specify this option, you must also specify the SHARING USER_INTERLOCK attribute unless you have specified the SHARING PROHIBIT attribute.

This attribute corresponds to the UFO option in the FAB$L_FOP field and is not supported for DECnet for OpenVMS operations.

WINDOW_SIZE

This attribute specifies the number of retrieval windows (pointers) you want RMS to maintain in memory for your file. You can specify a numeric value in the range 0 to 127, or 255. A value of 0 indicates that RMS is to use the system default number of retrieval pointers. A value of 255 means to map the entire file, if possible. Values between 128 and 254, inclusive, are reserved for future use.

This attribute corresponds to the FAB$B_RTV field and is not supported for DECnet for OpenVMS operations.

WRITE_CHECK

This switch specifies that disk transfers are checked by a read-compare operation. Note, however, that this operation creates extra system overhead.

This switch does not permanently mark the file for WRITE_CHECK; it sets an RMS run-time option. You must use the SET FILE/DATA_CHECK=WRITE command to mark the file permanently.

This attribute corresponds to the WCK option in the FAB$L_FOP field.

The KEY primary attribute acts as a header for a section of the FDL file that describes keys. You must specify a separate KEY section for each key of an indexed file. The number of the key being described follows the word KEY (for example, KEY 0, KEY 1, …KEY n). The KEY value for the primary key must be 0. The KEY value for secondary keys can be numbered from 1 to 254.

The KEY primary attribute corresponds to the XAB$B_REF field.

CHANGES

This switch allows an RMS Update operation to change the value of the key. Such a change is not allowed for the primary key (regardless of this attribute), so the default setting for primary keys is NO. With alternate keys the default setting is also NO, but you can specify YES to allow changes to alternate key values.

This attribute corresponds to the CHG option in the XAB$B_FLG field.

COLLATING_SEQUENCE

The name of the NCS collating sequence that defines the sorting order of the characters for this key. The value is a string from 1 to 31 characters long. You must supply the value; there is no default.

This attribute corresponds to the XAB$L_COLNAM field.

DATA_AREA

This numeric attribute identifies the area where you place the data records in an indexed file with multiple areas. The value is an integer in the range 0 to 254, which must be the same number as that assigned to the area in an AREA section.

The DATA_AREA, LEVEL1_INDEX_AREA, and INDEX_AREA values are used when the data level and the index levels are placed in separate areas or when each key is placed in its own area.

This attribute corresponds to the XAB$B_DAN field.

DATA_FILL

This attribute establishes the percentage of bytes in each data bucket in the area you want populated initially. If you anticipate that many records will be inserted randomly into the file, this value should be less than 100 percent of the bytes. The default value is 100 percent, and the minimum value is 50 percent. The /FILL_BUCKETS qualifier to the CONVERT command overrides this attribute.

This attribute corresponds to the XAB$W_DFL field except that XAB$W_DFL contains a byte count, not a percentage.

DATA_KEY_COMPRESSION

This switch compresses leading and trailing repeating characters in the primary key and its default value is YES. For compression to occur, your indexed file must be defined as a Prolog 3 file with the FDL attribute KEY PROLOG. However, KEY PROLOG 3 is the default.

This attribute corresponds to the KEY_NCMPR option in the XAB$B_FLG field, and should be set for DECnet for OpenVMS operations.

DATA_RECORD_COMPRESSION

This switch controls whether repeating characters are compressed in the data records. The default is YES; however, for compression to occur, your indexed file must be defined as a Prolog 3 file.

This attribute corresponds to the DAT_NCMPR option in the XAB$B_FLG field and should be set for DECnet for OpenVMS operations.

DUPLICATES

This switch controls whether duplicate keys are allowed in the indexed files. For primary keys, the default setting is NO, but for alternate keys, the default setting is YES.

Duplicate alternate keys can be useful. For example, sorting a customer file on an alternate key of a postal code is a common application and one that requires duplicate keys.

When duplicate keys are not allowed, any attempt to write a record where the key would be a duplicate results in an error.

This attribute corresponds to the DUP option in the XAB$B_FLG field.

INDEX_AREA

This numeric attribute identifies the area where you place the index levels (other than level 1) in an indexed file with multiple areas. The value is an integer in the range 0 to 254, which must be the same number as that assigned to the area in an AREA section.

The INDEX_AREA, DATA_AREA, and LEVEL1_INDEX_AREA values are used when the data level and the index levels are placed in separate areas or when each key is placed in its own area.

This attribute corresponds to the XAB$B_IAN field.

INDEX_COMPRESSION

This switch controls whether leading repeating characters in the index are compressed. The default value is YES; however, for compression to occur, your indexed file must be defined as a Prolog 3 file.

This attribute corresponds to the IDX_NCMPR option in the XAB$B_FLG field and should be set for DECnet for OpenVMS operations.

INDEX_FILL

This attribute sets the percentage of bytes in each index level bucket to be populated initially. If you anticipate that many records will be inserted randomly into the file, this value should be less than 100 percent. The default value is 100 percent and the minimum value is 50 percent.

The /FILL_BUCKETS qualifier to the CONVERT command overrides this attribute.

This attribute corresponds to the XAB$W_IFL field except that the XAB$W_IFL field contains a byte count, not a percentage.

LENGTH

This numeric attribute sets the length of the key in bytes. This value, along with the POSITION and TYPE attributes, is used when the key is unsegmented.

This attribute corresponds to the XAB$B_SIZ0 field. Its value must be specified because there is no default.

LEVEL1_INDEX_AREA

This attribute identifies the area where you place the level 1 index in an indexed file with multiple areas. The value is an integer in the range 0 to 254, which must be the same number as that assigned to the area in an AREA section.

When the data level and the index levels are placed in separate areas, or when each key is placed in its own area, use the LEVEL1_INDEX_AREA, DATA_AREA, and INDEX_AREA values.

This attribute corresponds to the XAB$B_LAN field.

NAME

This string attribute can be used to assign a name to a key. The name string is limited to 32 bytes and is padded with ASCII null characters. The default value is no name (blank).

This attribute corresponds to the XAB$L_KNM field.

NULL_KEY

This switch controls whether null key values will be allowed in an alternate string key field. The default value, NO, requires that all records contain a valid value for this alternate key.

In some databases, such entries are not desirable; some records will not contain a value for a particular alternate key. By allowing null keys, by declaring a null field, and by writing the null field as the alternate key for a record, you can include the record in the database.

A null key value is specified with the KEY NULL_VALUE secondary attribute. If a record has the specified null value in its alternate key field, a pathway to that record will not be made in the alternate index structure.

This attribute corresponds to the NUL option in the XAB$B_FLG field.

NULL_VALUE

This attribute specifies the null value that instructs the system not to create an alternate index entry for the record that has the null value in every byte of the key field. All data types may be used to specify null key values.

This attribute corresponds to the XAB$B_NUL field.

POSITION

This numeric attribute defines the byte position of the beginning of the key field, with the first position being 0. Primary keys work best if they start at byte 0. This attribute, along with the LENGTH and TYPE attributes, is used when the key is unsegmented.

This attribute corresponds to the XAB$W_POS0 field.

PROLOG

This numeric attribute defines the internal structure level of indexed files—PROLOG 1, PROLOG 2, and PROLOG 3.

Prolog 3 files accept multiple keys (or alternate keys) and all data types. They also give you the option of compressing your data, indexes, and keys. PROLOG 3 is the default.

On the other hand, Prolog 1 and 2 files do not allow these options. You should not specify Prolog 3 if the primary key is segmented and the segments overlap. If you want to use a Prolog 3 file in this case, consider defining the overlapping segmented key as an alternate key and then choosing a different key to be the primary key.

To specify a Prolog 3 file, assign the value 3 to this attribute. To specify a Prolog 1 or 2 file, assign the value 2. There is no perceivable difference between PROLOG 1 and PROLOG 2.

If you do not specify a value for this attribute, the utility that creates a data file from the FDL file uses the system or process default. To see these default values, enter the DCL command SHOW RMS_DEFAULT.

This attribute is not supported for DECnet for OpenVMS operations; the default prolog in effect at the remote node is used.

This attribute corresponds to the XAB$B_PROLOG field.

SEGn_LENGTH

This numeric attribute defines the length of the key segment in bytes and is used with the SEGn_POSITION attribute when the key is segmented. The value n is the number of the segment and may be 0 to 7. The first segment in the key must be numbered 0, and each key may have up to eight segments. Segmented keys must be STRING type.

For Prolog 3 files, segments cannot overlap.

This attribute corresponds to the key size fields, XAB$B_SIZ0 to XAB$B_SIZ7.

SEGn_POSITION

This numeric attribute defines the starting byte for a segment in a string key. The first position is 0 and segments cannot overlap in Prolog 3 files.

This attribute corresponds to the positioning fields, XAB$W_POS0 to XAB$W_POS7.

TYPE

The default key data type is STRING.

This attribute corresponds to the XAB$B_DTP field.

BLOCK_COUNT

A local node uses this numeric attribute to establish the size, in blocks, of a message buffer for messages between itself and a remote node. The value can be 0 to 127. By default, the local node uses the NETWORK BLOCK COUNT value for the process. If that value is 0, then the NETWORK BLOCK COUNT value for the system is used. Use the SHOW RMS command to see what the process and system values are for NETWORK BLOCK COUNT.

The BLOCK_COUNT attribute corresponds to the XABITM item code XAB$_NET_BLOCK_COUNT, the requested block count.

LINK_CACHE_ENABLE

This switch enables logical link caching. It corresponds to the XABITM item code XAB$_NET_LINK_CACHE_ENABLE.

LINK_TIMEOUT

This numeric attribute specifies the logical link timeout in seconds, from 0 to 65,535. It corresponds to the XABITM item code XAB$_NET_LINK_TIMEOUT.

NETWORK_DATA_CHECKING

This switch enables data access protocol (DAP) level cyclic redundancy check (CRC). It corresponds to the XABITM item code XAB$_NET_DATA_CRC_ENABLE.

BLOCK_SPAN

This switch determines whether records can span block boundaries in a sequential file. It corresponds to the BLK option in the FAB$B_RAT field.

When the switch is set to NO, records cannot be larger than 512 bytes. When the space remaining in a block is insufficient to store the next record, RMS stores the next record in a new block.

CARRIAGE_CONTROL

CONTROL_FIELD

This attribute specifies the size, in bytes, of the fixed-length control portion of VFC records. Its value must be a number in the range 1 to 255. The default value is 2.

This attribute corresponds to the FAB$B_FSZ field.

FORMAT

This attribute corresponds to the FAB$B_RFM field.

SIZE

Sets the maximum record size in bytes.

When used with fixed-length records, this value is the length of every record in the file.

When used with variable-length records, this value is the longest record that can be placed in the file. With sequential or indexed files, you can specify 0 and the system will not impose a maximum record length. (Note, however, that records in an indexed or relative file cannot cross bucket boundaries.)

When used with relative files, the SIZE attribute is used with the BUCKET_SIZE attribute to set the size of the fixed-length cells.

With VFC records, do not include the fixed control portion of the record in the SIZE calculation; only the data portion is set by this attribute. The RECORD CONTROL_FIELD attribute sets the size of the fixed control portion.

The fixed area is the size, in bytes, of the fixed-control portion of VFC records. Regular VFC records have a control field size of 0.

This attribute corresponds to the FAB$W_MRS field.

Table 4.1 gives the maximum record sizes, in bytes, for the various file organizations and record formats.

For DECnet for OpenVMS operations, the maximum record size is determined by the DCL command SET RMS/NETWORK_BLOCK_COUNT.

The SHARING section allows you to specify whether you want to allow multiple readers or writers to access your file at the same time. The SHARING keyword takes no values; it serves only to define this section.

DELETE

The process accessing a file uses this switch to permit other accessors to delete records from the file.

This attribute corresponds to the DEL option in the FAB$B_SHR field.

GET

The process accessing a file uses this switch to permit other accessors to allow other users to read the file (to perform Find or Get RMS services or the equivalent language statement that reads a record). SHARING GET is the default if you have also specified ACCESS GET.

This attribute corresponds to the Get option in the FAB$B_SHR field.

MULTISTREAM

This switch allows multistream access to a file and is relevant for record operations only. This attribute is not available for sequential files with other than 512-byte, fixed-length records.

This attribute is not supported for DECnet for OpenVMS operations; an error is returned if you try to use it.

This attribute corresponds to the MSE option in the FAB$B_SHR field.

PROHIBIT

The process accessing a file uses this switch to prohibit any type of file sharing by other accessors. The PROHIBIT attribute takes precedence over all other ACCESS secondary attributes; if you specify the DELETE, PUT, TRUNCATE, or UPDATE attribute in the ACCESS section, the PROHIBIT attribute defaults to YES.

This attribute corresponds to the NIL option in the FAB$B_SHR field.

PUT

The process accessing a file uses this switch to allow other users to write records to the file (to perform Put or Extend RMS services or the equivalent language statement that writes a record or extends the space allocated to a file).

This attribute corresponds to the PUT option in the FAB$B_SHR field.

UPDATE

The process accessing a file uses this switch to allow other users to update records currently existing in the file (to perform Update or Extend RMS services or the equivalent language statement that rewrites a record or extends the space allocated to a file).

This attribute corresponds to the UPD option in the FAB$B_SHR field.

USER_INTERLOCK

This switch allows one or more users to write to a sequential file or a shared file. Usually this attribute is used for a file that is open for block I/O and the user is responsible for any interlocking required. USER_INTERLOCK is specified with the DELETE, GET, PUT, and UPDATE attributes.

This attribute corresponds to the UPI option in the FAB$B_SHR field.

The SYSTEM section consists of system identification information and can be used to help document your FDL file. The SYSTEM keyword takes no values; it serves only to define this section.

DEVICE

This string attribute is used for comment purposes only. The intended use is to name the model of the disk on which the data file will reside.

SOURCE

TARGET

If you use EDIT/FDL to create your FDL file, the utility prompts you for a title during the session. The title is a string that you can place at the beginning of the FDL file. The character string you supply is for comment purposes only. It can be up to 132 characters long, including the TITLE keyword.

When the Edit/FDL and Analyze/RMS_File utilities create an FDL file, they place a header called the IDENT section after the TITLE in the FDL file. The IDENT attribute specifies the date and time of the creation of the FDL file, and it specifies the name of the utility that created it (either EDIT/FDL or ANALYZE/RMS_FILE).

However, you can also specify the header in the IDENT section. The character string that you supply can be up to 132 characters long, including the IDENT keyword. can contain one or more index levels from one or more keys.