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OpenVMS Record Management Utilities Reference
Manual
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.
If the alternate key is a string data-type key, you can specify the
null value either by enclosing the character in apostrophes or by
specifying an unsigned decimal number denoting the character's ASCII
value without enclosing characters.
Note
The string data-type keys include STRING, DSTRING, COLLATED, and
DCOLLATED.
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The default is the ASCII null character (0).
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
This attribute specifies the key type and must have one of the
following values:
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BIN2
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An unsigned, 2-byte, binary number in the range 0 to 65,535 (2
16--1).
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BIN4
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An unsigned, 4-byte, binary number in the range 0 to 4,294,967,295 (2
32--1).
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BIN8
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An unsigned, 8-byte, binary value that ranges from 0 to 2
64--1.
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COLLATED
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A string of ASCII characters. If the key is to be sorted by an NCS
collating sequence, then the key type must be declared as COLLATED or
as DCOLLATED (descending collated---sort in reverse order according to
the collating sequence for that particular key). The sort order is
determined by the collating sequence for that particular key.
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DBIN2
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An unsigned, 2-byte, binary value that ranges from 0 to 65,535 (2
16--1). In an indexed file, records are stored in descending
order for this key of reference.
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DBIN4
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An unsigned, 4-byte, binary value that ranges from 0 to 4,294,967,295 (2
32--1). In an indexed file, records are stored in descending
order for this key of reference.
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DBIN8
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An unsigned, 8-byte, binary value that ranges from 0 to 2
64--1. In an indexed file, records are stored in descending
order for this key of reference.
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DCOLLATED
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A string of ASCII characters. If the key is to be sorted by an NCS
collating sequence, then the key type must be declared as COLLATED or
as DCOLLATED (descending collated---sort in reverse order according to
the collating sequence for that particular key).
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DDECIMAL
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A packed-decimal value (that is, a continuous string of 1 to 16 bytes)
accessed in descending sort order in an indexed file. The format of the
DDECIMAL type is the same as for DECIMAL, described next (except that
DECIMAL is accessed in ascending order).
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DECIMAL
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A packed-decimal value, which is a continuous string of 1 to 16 bytes.
A DECIMAL value is specified by the address of the first byte of the
string and by the number of decimal digits.
Each byte in a DECIMAL value is divided into two 4-bit fields. Each
of these fields contains the binary representation of one decimal
digit, except for the first 4-bit field in the highest byte, which
represents the sign of the DECIMAL value.
Although 4 bits can represent values up to decimal 16 (a
hexadecimal 10), values greater than 9 are not allowed in a DECIMAL
4-bit field, except for the sign field.
The first byte contains the two beginning digits of the value. The
high-order nibble contains either the most significant digit or a
leading zero if it is needed to make the sign field appear in the
correct 4-bit field.
For example, a DECIMAL value of +123 has a length of 3 (for 3
digits) and requires 2 bytes of storage.
A DECIMAL value of --5237 would have a length of 4 digits. It would
need 3 bytes of storage.
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DINT2
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A signed, 2-byte integer accessed in descending order in an indexed
file. This data type can represent integers between --32,768 and
+32,767.
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DINT4
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A signed, 4-byte integer accessed in descending order in an indexed
file. This data type can represent integers between --2,147,483,648 and
+2,147,483,647.
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DINT8
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A signed, 8-byte integer accessed in descending order in an indexed
file. This data type can represent integers between --2
63 and +2
63--1.
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DSTRING
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A string of ASCII characters accessed in descending sort order in an
indexed file. The maximum length of the string is 255 characters.
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INT2
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A signed, 2-byte integer; this data type can represent integers between
--32,768 and +32,767.
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INT4
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A signed, 4-byte integer; this data type can represent integers between
--2,147,483,648 and +2,147,483,647.
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INT8
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A signed, 8-byte integer; this data type can represent integers between
--2
63 and +2
63--1.
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STRING
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A string of ASCII characters. The longest length allowed is 255
characters.
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The default key data type is STRING.
This attribute corresponds to the XAB$B_DTP field.
4.9 NETWORK Section
The NETWORK section sets run-time network access parameters. The
following table lists the NETWORK secondary attributes and their
default values. Note that all NETWORK secondary attributes are run-time
attributes.
| Secondary Attribute |
Default Value |
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BLOCK_COUNT
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Varies
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LINK_CACHE_ENABLE
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YES
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LINK_TIMEOUT
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30
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NETWORK_DATA_CHECKING
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YES
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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.
4.10 RECORD Section
The RECORD section contains secondary attributes that define various
controls for records. The RECORD keyword itself takes no value; it
serves only to begin this section. The following table lists the RECORD
secondary attributes and their default values. Note that all RECORD
secondary attributes are create-time attributes.
| Secondary Attribute |
Default Value |
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BLOCK_SPAN
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YES
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CARRIAGE_CONTROL
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CARRIAGE_RETURN
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CONTROL_FIELD
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2
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FORMAT
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VARIABLE
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SIZE
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No default
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BLOCK_SPAN
This switch determines whether records can span block boundaries in a
sequential file. It corresponds to the BLK option in the FAB$B_RAT
field.
When the switch is set to NO, records cannot be larger than 512 bytes.
When the space remaining in a block is insufficient to store the next
record, RMS stores the next record in a new block.
CARRIAGE_CONTROL
This attribute corresponds to the FAB$B_RAT parameter and must be one
of the following keywords:
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CARRIAGE_RETURN
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Specifies that each record is preceded by a line feed and is followed
by a carriage return when the record is written to a carriage control
device, such as a line printer or a terminal. This is the default.
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FORTRAN
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Specifies that the first byte (byte 0) of each record contains a
FORTRAN (ASA) carriage control character. The following lists the byte
0 values, the ASCII representation of each byte and the carriage
control interpretation.
Byte 0
Value |
ASCII |
Meaning |
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0
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Null
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Null carriage control. Sequence: print buffer contents.
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20
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Space
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Single-space carriage control. Sequence: line feed, print buffer
contents, carriage return.
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24
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$
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Prompt carriage control. Sequence: line feed, print buffer contents.
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28
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+
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Overprint carriage control. Sequence: print buffer contents, carriage
return. Allows double printing for emphasis.
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30
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0
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Double-space carriage control. Sequence: line feed, line feed, print
buffer contents, carriage return.
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31
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1
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Page eject carriage control. Sequence: form feed, print buffer
contents, carriage return.
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All
others
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Same as ASCII space character: single-space carriage control.
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NONE
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Specifies that no carriage control is to be provided.
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PRINT
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Specifies that the fixed control portion of VFC records contains
carriage control information. The first byte of the control portion
specifies the carriage control to be performed before printing. The
second byte specifies the control to be performed after printing.
The following table shows the encoding scheme for the control bytes
when you specify the PRINT keyword.
| B7 |
B6 |
B5 |
B4 |
Meaning |
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0
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0
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0
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0
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To specify no carriage control (NULL), set bits 3 to 0 at 0.
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0
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x
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x
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x
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Use bits 6 to 0 to specify a count of new lines (line feed followed by
carriage return).
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1
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0
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0
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x
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Output the ASCII C0 control character specified by the configuration of
bits 4 to 0.
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1
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0
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1
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x
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Reserved.
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1
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1
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0
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0
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Skip to the vertical format unit (VFU) channel (1-16) specified by bits
3 to 0. Devices that do not have hardware VFUs translate these codes as
a 1-line advance.
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1
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1
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0
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1
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Reserved.
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1
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1
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1
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0
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Reserved.
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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$B_FSZ field.
FORMAT
This keyword attribute establishes the record format for the data file.
Its value must be one of the following keywords:
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FIXED
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Specifies fixed-length records.
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STREAM
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Specifies that the records are STREAM records; the record is viewed as
a continuous stream of bytes, delimited by a special character. This
format is compatible with RMS--11 stream files. This is valid for
sequential files only.
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STREAM_CR
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Specifies that the records are STREAM records; the record is viewed as
a continuous stream of bytes, delimited by a CR character. This is
valid for sequential files only.
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STREAM_LF
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Specifies that the records are STREAM records; the record is viewed as
a continuous stream of bytes, delimited by an LF character. This is
valid for sequential files only.
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UNDEFINED
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Specifies undefined record format, which means that the record is a
continuous stream of bytes with no specific terminator. This keyword is
valid for sequential files only.
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VARIABLE
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Specifies variable-length records. This is the default setting.
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VFC
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Specifies variable-length records with fixed-length control fields
(VFC). This is valid for sequential and relative files.
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This attribute corresponds to the FAB$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.
Table 4-1 Maximum Record Size for File Organizations and Record Formats
| File Organization |
Record Format |
Maximum Record Size |
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Sequential
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Fixed-length
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32,767
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Sequential (disk)
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Variable-length
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32,767
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Sequential (disk)
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VFC
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32,767
1
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Sequential (disk)
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Stream
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32,767
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Sequential (disk)
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Stream CR
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32,767
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Sequential (disk)
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Stream LF
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32,767
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Sequential (ANSI Tape)
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Variable-length
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9,995
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Sequential (ANSI Tape)
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VFC
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9,995
1
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Relative
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Fixed-length
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32,255
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Relative
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Variable-length
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32,253
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Relative
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VFC
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32,253-FSZ
1
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Indexed, Prolog 1 or 2
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Fixed-length
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32,234
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Indexed, Prolog 1 or 2
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Variable-length
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32,232
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Indexed, Prolog 3
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Fixed-length
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32,224
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Indexed, Prolog 3
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Variable-length
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32,224
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1The maximum record size listed for the VFC record format is
for the data portion of the record only. It does not include the number
of bytes in the control area.
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