ISO 8211:1985

Information processing — Specification for a data descriptive file for information interchange

Traitement de l'information — Spécification d'un fichier de données descriptif pour l'échange de l'information

General Information

• Status: Withdrawn
• Publication Date: 11-Dec-1985
• Withdrawal Date: 11-Dec-1985
• ICS: 35.080 - Software
• Technical Committee: ISO/IEC JTC 1 - Information technology
• Drafting Committee: ISO/IEC JTC 1 - Information technology
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 29-Sep-1994
• Completion Date: 12-Feb-2026

Relations

• Revised: ISO/IEC 8211:1994 - Information technology — Specification for a data descriptive file for information interchange
• Effective Date: 15-Apr-2008

Standards Content (Sample)

International Standard 821 1
INTERNATIONAL ORGANIZATION FOR STANDAROIZATION*MEX(AYHAPOaHAR OPrAHH3AUHR Il0 CTAHflAPTH3AUHM.ORGANISATlON INTERNATIONALE DE NORMALISATION
information processing - Specification for a data
II)
descriptive file for information interchange
Traitement de Sin formation - Spécification d'un fichier de données descriptif pour l'échange de I'information
First edition - 1985-12-15
iz - UDC 681.3.04 Ref. No. IS0 8211-1985 (E)
Descriptors : data processing, information interchange, files, specifications.
-
ii
!i Price based on 27 pages
Foreword
IS0 (the International Organization for standardization) is a worldwide federation of
national standards bodies (IS0 member bodies). The work of preparing International
Standards is normally carried out through IS0 technical committees. Each member
body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, govern-
mental and non-governmental, in liaison with ISO, also take part in the work.
Draft International Standards adopted by the technical committees are circulated to
the member bodies for approval before their acceptance as International Standards by
the IS0 Council. They are approved in accordance with IS0 procedures requiring at
least 75 % approval by the member bodies voting.
International Standard IS0 821 1 was prepared by Technical Committee ISO/TC 97,
information processing systems.
Users should note that all International Standards undergo revision from time to time
and that any reference made herein to any other International Standard implies its
latest edition, unless otherwise stated.
0 international Organization for Standardization, 1985 0
Printed in Switzerland
Contents
Page
O Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1 Scope and field of application . . . . . . . . . . .
2 Conformance . .
3 References. . . . . . . . . . . . . . . . . . . . . .
4 Definitions . . . . . . . . . . . . . .
5 Interchange file .
6 Description of user data types and structures . . . . . . . . . . . 12
7 Coded character set extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Annexes
A 18
Guidelines for implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B Data field examples . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . 21
C 24
DDF model and logical record structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
iii
INTERNATIONAL STANDARD IS0 8211-1985 (E)
Information processing - Specification for a data
descriptive file for information interchange
O Introduction media chosen. It is assumed that variable-length records can be
processed by the supporting label and file processing system. It
This International Standard has been produced in response to requires a computer process capability to map the user file or
an identified need for a mechanism to allow data structures to
data base management system to the interchange file. This
be easily moved from one computer system to another, inde- mapping function has to provide the necessary data and struc-
pendent of make. Data structures required to be interchanged
ture conversions. The parameters required to define the selec-
can vary significantly in complexity and size, and a common tion and conversion of these data items and structures into the
method to accomplish these interchanges is desirable. It is also
formats specified by this International Standard are outside the
desirable that any medium such as a communication line, a scope of this International Standard. The interchange standard
magnetic tape, a disk pack, a flexible disk, etc., should be able
requires the use of the IS0 646 coded character set in control
to be used for the physical interchange and that, if possible, all fields and permits the use of extended character sets in user
information necessary to successfully recreate the structure in data fields.
the target system should be contained within the information
This International Standard provides for three interchange
transported on the medium.
levels from which the users may choose based on the complex-
ity of their data structures. The first interchange level supports
To meet these needs this International Standard specifies
multiple fields containing simple, unstructured character
medium-independent and system-independent file and data
strings. The second level supports level one and processes
record formats for the interchange of information between
multiple fields containing structured user data comprising a
computer systems. This International Standard is intended for
variety of data types. The third level supports level two and
use with physical recorded media as well as with communica-
hierarchical data structures.
tions media. The contents in the user data structure can be of
any internationally recognized character set and coding and are
NOTE - Additional information concerning the application of this
interchanged in a transparent fashion. The intermediate struc-
International Standard is given in annex A.
ture through which the information passes is designed for inter-
change purposes only and is not intended to be used for
general processing.
1 Scope and field of application
The aim when developing this International Standard was to
This International Standard specifies an interchange format to
define an interchange format into which the sender’s informa- facilitate the transfer of files containing data records between
tion is mapped and is conveyed to the receiver’s system. Upon
computer systems. It is not designed as a record format for in-
receipt of the information in the interchange format it is then
digenous files of any specific system, It defines a generalized
mapped into the receiver‘s format without loss of structure and structure which can be used to transmit, between systems,
content. This International Standard specifies a method for records containing a wide variety of data types and structures.
describing a robust interchange structure which can accept It provides the means for the description of the contents of data
most user data structures. The method enables the sender to
records but does not define their contents.
preserve structure information and to convey it to the receiver
This International Standard specifies
with the data so that the receiver can remap the structure and
data into the local system.
a) media-independent file and data record descriptions for
information interchange. It assumes the use of other Inter-
Most data structures in common use can be described and
national Standards for labelling and file structure such as
interchanged using this International Standard. The structures
IS0 1001, IS0 4341, IS0 7665;
within the interchange file can be of the following forms :
elementary data, vectors, arrays and hierarchies. User file
b) the description of data elements, vectors, arrays and
structures such as sequential, hierarchical, relational and in-
hierarchies containing character strings, bit strings and
dices can be converted into the interchange structure. Network
numeric forms. The numeric forms are specified by
structures can be interchanged but additional pre-processing
IS0 6093;
and post-processing is necessary to preserve logical linkages.
c) a data descriptive file comprising a data descriptive
This International Standard is medium-independent and re-
record and companion data records that enable information
quires an environment in which International Standard labels
interchange to occur with minimal specific external descrip-
and file structures can be written on or read from the standard
tion:
IS0 8211-1985 (E)
NOTE - The characters specified in this international Standard are
d) the data descriptive record that describes the
represented by their position (column/row) in the coded character set
characteristics of each data field within the companion data
table of IS0 646, or by their acronyms, Le., ESC, RS, US, and SP.
records;
e) three levels of interchange depending on the complexity
4.2 array descriptor: A sequence of numbers which
of the allowed structure (see 5.2.1.2).
specifies the number of dimensions and extent of an array.
4.3 base address of data : A data element the value of
2 Conformance
which is equal to the byte count up to the first data field follow-
ing the field terminator of the directory, where the specified
Interchange files shall be in conformance with this International
(O) is the first byte of the leader.
origin
Standard when all of the data descriptive records and data
records conform to the specifications of this International Stan-
4.4 bit field : A data field Comprising only binary digits and,
dard. A statement of conformance shall specify the interchange
when necessary, filled on the right with binary zeros to com-
level to which the contents of files conform.
plete a byte. See also character mode bit string.
This International Standard does not specify requirements for
processing and implementation, therefore this processing can-
4.5 byte : A collection of n bits.
not itself conform to this International Standard.
NOTE - This International Standard is media-independent and the
number of bits will be media-dependent.
3 References
4.6 Cartesian label : An array of identifiers formed by
IS0 646, Information processing - IS0 7-bit coded character
the Cartesian product of the elements of two (or more) vector
set for information interchange.
labels. The array elements have thzsameorder as the elements
2f the direct product su5h that if a and b are the vector labels,
IS0 1001, Information processing - Magnetic tape labelling
a = [aiJi$ ., a(n)l and b = [MI), ., b(m)l, then the Cartesian
and file structure for information interchange.
label, a4 = iaU)b(li, a(l)b(2), ., a(l)b(m), ., a(n)b(m)l
where a(i)b(i) is a concatenation of di) and b(i) which forms an
IS0 2022, Information processing - IS0 7-bit and 8-bit coded
identifier of the i,j element of a corresponding data array.
character sets - Code extension techniques.
4.7 character mode bit string : A sequence of characters
IS0 4341, Information processing - Magnetic tape cassette
(O or 1) that represents a string of binary digits. (See also bit
and cartridge labelling and file structure for information inter-
field.)
change.
IS0 6093, Information processing - Representation of
4.8 compound data field : A field comprising one or more
numerical values in character strings for information inter-
elementary data elements.
change. ’)
data descriptive file: DDF : A file containing a data
IS0 7665, Information processing - File structure and labelling 4.9
descriptive record and its companion data records.
of flexible disk cartridges for information interchange.
The following document is also relevant to this International
4.10 data descriptive record: DDR : A record that logically
Standard :
precedes the data records and contains the control parameters
and data definitions necessary to interpret companion data
IS0 international register of character sets to be used with
records. The data descriptive record is the first logical record of
escape sequences.
a file other than the file labels (if applicable).
4.11 data record; DR : A logical record containing user
4 Definitions
data.
For the purposes of this International Standard the following
4.12 delimited structure : A structure composed of a col-
definitions apply.
lection of data elements that are separated by delimiters.
4.1 alphanumeric character : A character occurring in
4.13 delimiter: A single character that separates data
columns 2 to 7 inclusive [except position (7/15)1 of the Inter-
elements and data fields. (See table 1 for the use of delimiters.)
national Reference Version of IS0 646.
1) At present at the stage of draft.
IS0 8211-1985 (E)
to map : To establish the correspondence between the
4.14 directory : A table of identifiers and references to cor- 4.29
responding items of data. elements of two structures.
null : Pertaining to the condition of non-occurrence of
4.15 directory entry : A fixed-length field within the direc- 4.30
an entity, usually a data element, string or set.
tory that contains information about the tag, the length and the
location of a specific field for a given record.
4.31 preorder traversa1 sequence: A sequence of the
nodes of a hierarchy produced by the following recursive
4.16 elementary : Having the property of being indivisible
algorithm :
without loss of meaning.
a) enter the tree at the root node:
4.17 entry map : A field in the leader that is used to indicate
the structure of the entries in the directory.
b) traverse the left-most subtree not previously traversed;
c) if b) is not possible, return to the node superior to the
4.18 escape character; ESC : A control character which is
subtree and go to b).
It alters the meaning of a
used to provide additional characters.
limited number of contiguously following bit combinations.
record length : A data element the value of which is
4.32
The use of this character is specified in IS0 2022.
equal to the length in bytes of the record.
field terminator; FT : A character used to terminate a
4.19
relative position; RP : The position of a byte express-
4.33
field within a record, (1/14) in IS0 646.
ed as a decimal integer relative to the beginning of a field.
The first relative position is numbered "O".
file : A collection of related records treated as a unit.
4.20
tag : An identifier in a directory entry used to specify
4.34
4.21 file title : A string of characters that provides a
the internal name of an associated field.
displayable descriptive title for the interchange file.
This need not be the same as the file name.
4.35 unit terminator; UT: A character used to delimit
several types of subfields within variable-length fields in both
DDR and DR, (1/15) in IS0 646.
4.22 hierarchy; hierarchical structure : A rooted, ordered
tree structure comprising a superior root node with successive
multiple ordered subtrees at increasingly inferior nodes,
4.36 variable-length field : A field the length of which
ultimately terminating in leaf nodes.
varies from occurrence to occurrence.
4.23 interchange level; level : The designation of a
4.37 vector label : A vector the elements of which are labels
prescribed subset of the requirements of this International
(i.e., "column" headings or "row" headings) used to identify
Standard.
each element in a vector of data elements.
4.24 interchange format : A format for the exchange, as
opposed to the local processing, of records.
5 Interchange file
4.25 label : A character string used to identify or name a
5.1 General structure
field or subfield and its contents.
This subclause specifies the general structure of the inter-
change file and subsequent subclauses provide the detailed
4.26 leader : A fixed-length field that occurs at the begin-
ning of each record and provides parameters for the processing specifications. Figure 1 shows a schematic representation of a
file and the file labels.
of the record.
location : The byte count to the position of the first
4.27
IS0 standard file labels
byte of a field.
Data Descriptive File : Data Descriptive Record
Locations in the leader and directory are relative to the first (O)
Data Records
byte of the leader, and the location for data descriptive fields
IS0 file termination indicator
and user data fields are relative to the base address of data.
logical record; record : A collection of related data
4.28
Figure 1 - File and file label schematic representation
elements independent of their representation on a medium.
IS0 8211-1985 (E)
Each data descriptive field of the DDR contains a data descrip-
This International Standard specifies multiple Data Descriptive
tion of the user data in a DR user data field having the same
Files (DDFs), each comprising logical records with the required
tag. The DDR (but not the DR) has a special tag O.O and a
IS0 interchange file labels or headers for the particular
corresponding field which contains field controls, an optional
medium. Each file shall consist of the following logical records :
file title and in the case of a hierarchy, structure information.
The DRs have a special field to identify a record and the DDR
a) the Data Descriptive Record (DDR), and
contains a description of this field in the data descriptive field
having the same tag (O . 1). The contents of a DDR variable-
b) the Data Records (DRs). ,
length field vary depending upon the values of parameters in
the DDR leader.
The overall structure shall be as shown in figure 2, which is an
expanded logical schematic representation of the DDR and DR,
the leaders and directories of each record, typical records and a
2 are for
The DDR data descriptive fields shown in figure
typical data field for each record. The DDR and DR records
elementary character data fields and those shown in figure 12 are
shall have the same leader, directory, field and record structure
for compound data fields with all optional subfields included.
although their contents vary. A provision is made to omit the
repetition of identical DR leaders and directories for the inter-
NOTES
change for repetitive, fixed-format data.
1 The contents of a DR user data field may be highly varied, depend-
ing upon its description in the DDR; no example is given in figures 2
NOTES
and 12. See annex B for examples of data fields.
1 The logical juxtaposition of fields is shown and the meaning of
2 Throughout the remainder of this International Standard the length
some pointers and field lengths is indicated. For a physically sequential
of fields, except for bit fields, is given in bytes whose length in bits may
medium, figure 2 represents its physical order.
be media-dependent. The contents of fields are referred to as
characters, and multiple byte character sets are permitted in user fields
2 The special field tags specified in this International Standard arc?
(see 7.1.4). Therefore in these cases the field length is not equal to the
described in the following format : O.n where "n" is a decimal
number of characters.
number and "O ." implies sufficient zeros on the left to fill the tag field.
IS0 8211-1985 (El
DDR detail
schematic
File DDR gross
Detail of entry map,
label schematic
Entry, and
and
file
Data descriptive
structure
fields
I I Inline code 11
Size of I I
field length
descriptive area
Leader
standard
character set
file
indicator
labels
Directory
Entry (O1
record
Field tag (21
descriptive Entry (21 Field length
:: I
Continued
Field position
L
to DR
Examples for
(next
level 1 file
pagel
field (O1
See figure 12 for examples
Examples for data
of data descriptive fields
fields containing
for level 2 files containing
Data description elementary text
compound data fields.
of record
..
L
Data descriptive Data field name
field (21
Data descriptive Data field name
NOTES
1 Separator characters
FT = Field Terminator
2 Fixed field lengths are given in bytes to the right of each field.
3 Tags, their corresponding entries and fields are designated by (il.
Figure 2 - Expanded logical schematic representation of data descriptive file
IS0 8211-1985 (E)
DR detail Detail of entry map,
DR gross schematic
schematic
Entry, and
Data descriptive
fields
Leader
identifier
Reserved
Continued
from
Base address
field position
previous
124 Leader
of data area
Reserved
I page I
Size of
Entry map
4 field tag
Data record
Entry (1)
(Typical)
Entry (2)
Field tag (2)
---
Field length
Entry (ni
Field position
FT 1-
Record
Data record
identifier
field ( 1 )
File
termination
FT 1 (Typical)
L
User data
field in)
Figure 2 - Expanded logical schematic representation of data descriptive file (concluded)
IS0 8211-1985
E)
5.2.1.1 Record length field (DDR RP O to 4)
5.2 Data Descriptive Record (DDR)
This field shall specify the total length of the DDR in bytes. The
The DDR shall consist of the areas and terminators shown in
contents of this field shall be digits. A DDR length of O will
figure 3 and shall be the first record of the file.
signify a length in excess of 99 999.
Name of area 1 Length I
5.2.1.2 Interchange level field (DDR RP 5)
Leader 24
This field shall specify the level of the interchange file as
specified in clause 8. The content of this field shall be the digit
Directory kxp
1, 2 Or 3.
Field terminator 1
The value
Data descriptive area variable
1 shall mean that the file conforms to a level 1 file:
Field terminator
I 1 I
2 shall mean that the file conforms to a level 2 file;
Figure 3 - DDR schematic 3 shall mean that the file conforms to a level 3 file.
A level 1 file shall contain elementary character data fields
Each of the logical records shall consist of (see 6.1) but not compound data fields nor hierarchical struc-
tures. A level 2 file shall contain compound data fields (see 6.2)
but not hierarchical structures. A level 3 file shall
a) a leader of 24 characters;
contain compound data fields and a list of the tag pairs
(see 5.2.3.1.2) describing the hierarchical structures.
b) a directory of length k x p, terminated by a field ter-
minator, (1/14), where k is the number of directory entries
and p is the length of each entry (see 5.2.2); and
5.2.1.3 Leader identifier field (DDR RP 6)
cl a set of k variable-length fields, each terminated by a
This field shall specify that this record is the DDR and shall con-
field terminator, (1/14).
tain the character ’I”.
5.2.1 DDR leader
5.2.1.4 lnline code extension indicator (DDR RP 7)
The DDR leader shall consist of the fields shown in figure 4 and
This field shall indicate if inline escape sequences are used in
is further specified in 5.2.1.1 to 5.2.1.9.
data fields to designate extended coded character sets as
specified in IS0 2022.
UP Name of field Length Contents
The value
O Record length 5 digits
SP shall mean that no extensions are used;
5 Interchange level 1 digit
E shall mean that extensions are used.
6 Leader identifier 1 character
I I I
5.2.1.5 Reserved for future standardization (DDR RP 8)
lnline code extension
1 1 I character
indicator
I I l
This field is reserved for future Standardization.
8 I Reserved’) 1 SPACE character
5.2.1.6 Application indicator field (DDR RP 9)
Application indicator character
This field is reserved for future standardization and shall con-
tain the character SPACE.
digits
5.2.1.7 Field control length field (DDR RP 10 and 111
Code character set
1 3 1 characters
indicator
This field shall specify the number of bytes of the data descrip-
20 Entry map 4 digits tive field devoted to data element type and structure codes,
delimiters, and other positions reserved for future standardiza-
tion (see 5.2.3.1.1).
1) Reserved for future standardization.
The contents of this field shall be the digits 00, 03, 06 or O9
(see 5.3.3.2 and 7.1.3).
Figure 4 - DDR leader schematic
IS0 8211-1985
E)
5.2.1.10.3 Reserved for future standardization (DDR RP 22)
5.2.1.8 Base address of data descriptive area
(DDR RP 12 to 16)
This field is reserved for future standardization as an extended
entry map and shall be the digit "O".
This field shall specify the position of the first data descriptive
field of a DDR.
5.2.1.10.4 Size of field tag field (DDR RP 23)
NOTE - The first data descriptive field will be the file control field or
the record identifier field.
This field shall specify the size in bytes of the field tag subfield
of the directory entries and shall be a digit in the range of "1" to
The contents of this field shall be digits and shall be equal to the
"7' inclusive.
combined length in bytes of the leader and directory including
the field terminator at the end of the directory.
NOTE - For the purposes of 5.2 the following nomenclature is used :
m is the size of the field length subfield;
5.2.1.9 Extended character set indicator field
n is the size of the field position subfield;
(DDR RP 17 to 19)
f is the size of the field tag subfield.
This field shall specify the use of default coded character set ex-
tensions in the file.
5.2.2 DDR directory
The values in this field shall have the following meanings :
The DDR directory shall consist of repeated DDR directory en-
tries, the subfield lengths of which shall be specified in the
a) (2/0)(2/0)(2/0) : Only the International Reference
entry map. The DDR directory shall contain one DDR directory
Version of IS0 646 character set has been designated as the
entry for each data descriptive field and shall end with a field
default for the file.
terminator, (1/14). The DDR shall define all DR tags.
b) (2/0)(2/1)(2/0) : Extended character sets have been
The DDR directory entry specifies the location and length of a
designated as the default for one or more data fields (see
corresponding data descriptive field and shall consist of the
7.1.1).
subfields shown in figure 6. Each entry shall contain a field tag,
field length and field position, in that sequence and shall con-
c) Truncated escape sequence : An extended character
sist of m + n + t bytes.
set has been designated as the default for the entire file (see
7.1.2).
The DDR directory entries shall be in one to one cor-
respondence with the data descriptive fields. For hierarchical
5.2.1.10 Entry map field (DDR RP 20 to 23)
data structures (see 5.2.3.1.31, the directory entries of the DDR
shall be in the same order as the pre-order traversal sequence of
This field specifies the lengths of directory entry subfields and the generic data tree.
shall consist of the subfields shown in figure 5 (see 5.2.2).
Each subfield of this field shall contain a single digit.
Field tag alphanumeric
RP Name of field Length Contents
p(i- 1) +I Field length
20 Size of field length 1 digit
digits
digit
where
digit
digit p = t + m + nand;
i = the index of the directory entry.
Figure 5 - DDR entry map schematic
Figure 6 - DDR directory entry schematic
5.2.1.10.1 Size of field length field (DDR RP 20)
5.2.2.1 DDR field tag field
This field shall specify the size in bytes of the field length sub-
field of the directory entries and shall be a digit in the range of
This field shall contain a field tag identifying a data descriptive
"1" to "9' inclusive.
field and shall consist of between one and seven alpha-
numeric characters. The same field tag shall occur only once
5.2.1.10.2 Size of field position field (DDR RP 21)
within the DDR.
This field shall specify the size in bytes of the field position sub-
5.2.2.1.1 Field tag O.O shall identify the optional file control
field of the directory entries and shall be a digit in the range of
field and if present shall occut'only in the DDR.
"1" to "9' inclusive.
IS0 8211-1985 (E)
5.2.3.1.1 Field control field
5.2.2.1.2 Field tag 0.1 shall occur once in each record and
shall identify the record identifier field.
This field shall be present only in level 2 and level 3 files and its
length is specified by the field control length (DDR RP 10 and
5.2.2.1.3 If used, field tag 0.2 shall identify an optional user
11) (see 5.2.1.7). These controls shall not be used in the title
field of the DDR which has no corresponding data field in the
control field and shall have the value O or spaces (see 6.2.2).
DR. An implementation shall pass this field to the user for pro-
cessi ng.
5.2.3.1.2 File title field
NOTE - The contents of this field should be determined by the user
This field shall specify an optional file title following the field
and may be used to convey any augmented file description (for exam-
controls. It shall contain an optional character string which
ple file attributes relevant to the interchange) or ancillary file processing
shall be an external descriptive name of the interchange file.
controls or application information.
5.2.3.1.3 List of tag pairs
5.2.2.1.4 Field tags 0.3 through 0.9 shall be reserved for
It
future standardization. The list of tag pairs shall describe the hierarchical structure.
shall follow the file title field and shall be preceded by a unit ter-
minator, (1/15). The pairing of the tags shall be determined by
5.2.2.1.5 When present, tags O.O to 0.9 inclusive shall
the structural order from root node to leaf node in the generic
occur first in the DDR directory and in ascending numeric
data structure. These pairs may be placed in the list in any
order.
sequence and shall be contiguous. The root tag shall be the tag
of the record identifier field, 0.1. Tags 0.2 to 0.9 inclusive
5.2.2.2 DDR field length field
shall not participate in the structure specification.
NOTE - The variable hierarchical data structures permitted in the DRs
This field specifies the length in bytes of the field to which it
are described by supplying the pre-order traversal sequences of the
corresponds. This field shall contain a right-justified integer
data tree and a list of the tag pairs expressing the superior/subordinate
filled with leading zeros. The length of the field shall include the
logical association between the nodes of the data tree. The data struc-
field terminator.
tures of the DRs shall be derived from the generic data tree by the
repetition or deletion of nodes and subtrees. The pre-order traversal
sequence of the generic data tree is supplied by the order of the DDR
5.2.2.3 DDR field position field
directory entries (see 5.2.2). The pre-order traversal sequence of each
instance of a derived data tree in a DR is supplied by the sequence of
This field specifies the relative position of the first byte in the
directory entries in the DR (see 5.3.2). See annex C for further explana-
field referenced by the entry. This field shall contain a right-
tion of ordered tag pairs.
justified integer filled with leading zeros. It shall be relative to
the base address of the data descriptive area as specified in
5.2.3.2 Description of record identifier field (tag = 0.1)
DDR RP 12 to 16. The first byte of the first field following the
directory shall be numbered O.
The data descriptive area shall contain a data descriptive field
describing the record identifier field of the DR. This data
descriptive field shall comply with the requirements for descrip-
5.2.3 Data descriptive area
tive fields which describe user data fields as given in 5.3.3 and
The data descriptive area shall contain in its data fields that in-
clause 6.
formation which defines and describes the corresponding (i.e.,
having the same tag) data fields of the DR and provides control
5.2.3.3 Description of user data fields
parameters for automated processing. These fields shall have a
The data descriptive area shall contain a data descriptive field
specified format determined only by the DDR leader contents.
for each of the user data fields. These data descriptive fields are
All fields shall end with a field terminator, (1/14).
specified in clause 6.
5.2.3.1 File control field (tag = O.O)
5.3 Data record (DR)
The file control field shall contain the following subfields :
The data records shall consist of the areas and terminators
shown in figure 8.
a) the field controls (if any);
b) an optional file title, and
Name of area
I
c) a list of ordered tag pairs (only for hierarchical records)
I Leader I 24 I
(see figure 7).
I Directory I k' x P' I
1 Field terminator I 1 I
This field shall be terminated by the field terminator, (1/14).
I User data area I variable I
Field terminator 1
I
Field controls File title U List of tag pairs F
T T
where k' is the number of directory entries and p' is the
number of bytes in a directory entry of the DR.
Figure 7 - File control field schematic Figure 8 - DR leader schematic
IS0 8211-1985 (E)
For an interchange file consisting of variable length records 5.3.1.5 Base address of user data area (DR RP 12 to 16)
followed by fixed-length records comprising only fixed-length
data fields in which the DRs have identical leader and directory This field shall specify the position of the first user data field of
DR record.
values, the leader and directory of the first DR having a leader a
and directory identical to the remaining DRs shall apply to all
subsequent DRs. The leader and directory of the subsequent NOTE - The first user data field will be the record identifier field.
DRs may be omitted.
5.3.1.6 Reserved for future standardization (DR RP 17 to 19)
5.3.1 DR leader
This field is reserved for future standardization.
Each DR leader shall consist of the fields shown in figure 9 and
are further specified in 5.3.1.1 to 5.3.1.7.
5.3.1.7 Entry map field (DR RP 20 to 23)
This field specifies the lengths of directory entry subfields
UP I Name of field I Length 1 Contents I
within each DR and shall consist of the subfields shown in
figure IO.
O Record length 5 digits
Each subfield of this field shall contain a single digit.
Reserved for future
1 1 I SPACE character
standardization
l
Leader identifier 1 character
UP Name of field Length Contents
Reserved for future 20 Size of field length 1 digit
1 5 1 SPACE characters
standardization
I
21 Size of field position 1 digit
12 Base address of data 5 digits
I l l
digit
22 Reserved for future standardization 1
I
Reserved for future
I 3 1 SPACE characters
23 Size of field tag 1 digit
standardization
I
Entry map 4 digits
I
Figure 9 - DR leader schematic
5.3.1.7.1 Size of field length field (DR RP 20)
5.3.1.1 Record length field (DR RP O to 4) This field shall specify the size in bytes of the field length sub-
field of the directory entries and shall be in the range of "1" to
This field shall specify the total length of the DR in bytes. The "9" inclusive.
contents of this field shall be digits. A DR length of O will signify
a length in excess of 99 999.
5.3.1.7.2 Size of field position field (DR RP 21)
5.3.1.2 Reserved for future standardization (DR RP 5) This field shall specify the size in bytes of the field position sub-
field of the directory entries and shall be in the range of "1" to
This field is reserved for future standardization. "9' inclusive.
5.3.1.7.3 Reserved for future standardization (DR RP 22)
5.3.1.3 DR leader identifier field (DR RP 6)
This field is reserved for future standardization as an extended
This field shall specify that the record is a DR and shall specify
"0".
the repetitive characteristics of the subsequent DR leaders and entry map. Its value shall be the digit
directories. The values in this field shall have the following
meanings :
5.3.1.7.4 Size of field tag field (DR RP 23)
D means that a leader and directory will be found in the
This field shall specify the size in bytes of the field tag subfield
subsequent DR;
of the directory entries and shall be in the range of "1" to "7"
inclusive. The value in this field shall be equal to the value of
R means that a leader and directory will not be found in
the DDR size of field tag field.
the DRs subsequent to the current DR and that the leader
and directory of the current DR shall be applied to each
NOTE - For the purposes of 5.3 the following nomenclature is used :
subsequent DR.
rn' is the size of the field length subfield:
n' is the size of the field position subfield:
5.3.1.4 Reserved for future standardization (DR RP 7 to 11)
t is the size of the field tag subfield.
This field is reserved for future standardization.
IS0 8211-1985 (E)
DR RP 12 to 16. The first byte of the first field following the
5.3.2 DR directary
directory shall be numbered O.
The DR directory shall consist of repeated DR directory entries,
the subfield lengths of which shall be specified in the entry
5.3.3 User data area
map. The DR directon/ shall contain one DR directory entry for
The data fields of the user data area shall contain the user infor-
each user data field and shall end with a field terminator,
mation to be interchanged. Each data field shall be an instance
(1/141. All DR tags shall be defined in the DDR.
of the user data structure and data types defined by the DDR
The DR directory entry specifies the location and length of a data descriptive field with the corresponding field tag. The sub-
coriesponding user data field and shall consist of the subfields fields shall contain the data elements corresponding to the
shown in figure 11. Each entry shall contain a field tag, field labels contained in the corresponding DDR subfields. Each field
shall end with the field terminator, (1/14). In a delimited struc-
length and field position, in that sequence and shall consist of
m' + n' + tbytes. ture, where the delimiter character of subfields is (1/151, miss-
ing data elements shall be represented by successive deiimiters.
The DR directory entries shall be in one to one correspondence
A terminal string of adjacent subfield delimiters may be replac-
with the user data fields. Except for tag 0.1, a tag may be
ed by a field terminator, (1/141. Elementary character data
repeated in a DR directory. For non-hierarchical structures,
fields whose termination is determined by a field length, format
repeated tags shall be logically contiguous in a DR directory
width, user determined delimiter or field terminator may con-
and the DR tags shall occur in the same order as the tags of the
tain a unit separator character which shall be treated by an im-
DDR. The tags corresponding to missing user data fields may
plementation as a user data character.
be omitted from the directory unless required to describe struc-
The description of the user data is further defined in clause 6.
ture. For hierarchical data structures (see 5.2.3.1.31, the direc-
tory entries of the DR shall be in the same order as the pre-
order traversal sequence of the corresponding data fields of the
5.3.3.1 Record identifier field (tag = 0.1)
derived data tree of that DR.
Each DR shall contain exactly one record identifier field. The
content of the DR record identifier field shall conform to the
RP Name of field Length Contents
corresponding DDR data descriptive field and it shall be unique
within the file. Each identifier field shall be left-justified and filled
p(i- 1) Field tag t alp hanumeric
on the right by spaces (2/0) if the field is alphanumeric, and
right-justified and filled on the left by zeros (3/0) if numeric.
p(i- 1) +t Field length rn' digits
NOTE - See clause A.3 to annex A for further discussion of unique
I p(i- 1 i + ff rn' I Field position I n' I digits I identifiers.
where
5.3.3.2 User data fields
p = t + m' + n' and;
5.3.3.2.1 Elementary character data fields
i = index of the directory entry.
The user data fields of the DR shall contain a single string of
characters terminated by the appropriate field terminator (see
11 - DR directory entry schematic
Figure
table 1).
Interchange files composed solely of user data fields of this
5.3.2.1 DR field tag field
structure and type shall have the following control characters in
their DDR leader :
This field shall contain a field tag identifying a data field and
Leader field RP Characters
shall consist of between one and seven alphanumeric
characters.
Application indicator 9 SP
Field control length 10 and 11 O0
Field tag 0.1 shall occur once in each DR, shall identify the
record identifier field and shall occur first in the DR directory.
The remaining DDR leader fields are specified in 5.2.1.
5.3.2.2 DR field length field 5.3.3.2.2 Compound data fields
The data in these fields shall be characters, delimiters and bit
This field specifies the length in bytes of the field to which it
strings which conform to the specifications given in the cor-
corresponds. This field shall contain a right-justified integer
responding data descriptive field (see 6.2).
filled with leading zeros. The length of the field shall include the
field terminator.
Interchange files composed solely of fields of these structures
shall have the following control characters in their DDR leader :
5.3.2.3 DR field position field
Leader field RP Characters
This field specifies the relative position of the first byte in the
Application indicator 9 SP
field referenced by the entry. This field shall contain a right-
Field control length 10 and 11 O6
justified integer filled with leading zeros. It shall be relative
The remaining DDR leader fields are specified in 5.2.1.
to the base address of the data descriptive area as specified in
IS0 8211-1985 (E)
6 Description of user data types and field name, subfield labels for vectors and arrays, and data field
structures format information as specified in 6.2.1 to 6.2.4 and 7.1.
6.2.1 Data descriptive fields
6.1 Description of elementary character data
fields
The data descriptive fields for compound data fields shall com-
prise the field control field, the data field name, data element
This subclause specifies the method for the description of user
labels and data formats. These are shown schematically in
data comprising elementary character strings.
figure 12. The field controls, names, labels, and formats of the
permitted data structures and types are given in tables 1 and 2
and further specified in this clause. Table 1 specifies the use of
Data descriptive field : The data descriptive field for elemen-
delimiters. Table 2 specifies the format of the data descriptive
tary data fields shall contain only an elementary character string
field. The allowable data types described by the data descrip-
constituting the name of the user data field (see figure 2).
tive field are
Me Contents
6.2 Description of compound data fields
character character strings
implicit point implicit point numeric
This subclause specifies the method for the description of com-
representations
pound structures and data types which are more complex than
explicit point unscaled explicit point numeric
those covered by 6.1.
representations
explicit point scaled
scaled explicit poinj numeric
The data structures specified in this subclause shall be elemen- representations
character mode bit string digits O and 1
tary, vector and array structures containing character strings,
implicit point, explicit point, explicit point scaled, character bit field binary digits
mode bit string, bit field, and mixed data types. The data mixed types one or more of the above data
descriptive field shall contain control information, delimiters,
types
I l2
IS0 8211-1985 (E)
Data descriptive Detail of data
area descriptive fields
Continued from * These field
controls are
null and not
used
Example assumes
an elementary
identifier field data field
Example assumes
a vector field
I
--
LE3 Format controls
L
-
Data descriptive Field controls Example assumes
field in)
an array field
Data field name
FT 1
L -
- UT
Cartesian label
UT
Format controls
-
Figure 12 - Level 2 data descriptive area schematic representation
IS0 8211-1985 (E)
Table 1 - Delimiters and their uses
Print
Information
Use
Record
SeDarator symbol
DDR, DR Field terminator (FT)
(RS) 1/14''
Unit terminator (UT)
(US) 1/15') &
DR a) to delimit subfields in a data field not specified
by a format
DDR b) to pre- and post-del
...