United Nations Directories  for Electronic Data Interchange for
Administration, Commerce and Transport



UN/EDIFACT






                                           Message Type : IMPDEF
                                           Version      : D
                                           Release      : 01C
                                           Contr. Agency: UN

                                           Revision     : 1
                                           Date         : 2001-11-07






SOURCE: D13 Directory and Management Support Services (SWG)



                               CONTENTS

              EDI implementation guide definition message

0.     INTRODUCTION

1.     SCOPE

       1.1   Functional definition

       1.2   Field of application

       1.3   Principles

2.     REFERENCES

3.     TERMS AND DEFINITIONS

       3.1   Standard terms and definitions

       3.2   Message terms and definitions

4.     MESSAGE DEFINITION

       4.1   Segment clarification

       4.2   Segment index (alphabetical sequence by tag)

       4.3   Message structure
             4.3.1 Segment table











----------------------------------------------------------------------
For general information on UN standard message types see UN Trade Data
Interchange Directory, UNTDID, Part 4, Section 2.3, UN/ECE UNSM
General Introduction
----------------------------------------------------------------------



0.     INTRODUCTION

       This specification provides the definition of the EDI
       implementation guide definition message (IMPDEF) to be used in
       Electronic Data Interchange (EDI) between trading partners
       involved in administration, commerce and transport.

1.     SCOPE

1.1    Functional definition

       The EDI implementation guideline definition message (IMPDEF)
       permits the exchange of implementation details of an EDI
       message, including its usage and its presentation.

1.2    Field of application

       The EDI implementation guide definition message may be used for
       both national and international applications. It is based on
       universal practice related to administration, commerce and
       transport, and is not dependent on the type of business or
       industry.

1.3    Principles

       The IMPDEF message provides an EDI mechanism for describing the
       contents of a specific Message Implementation Guideline (MIG)
       or Implementation Convention (IC) for an EDI message that is
       capable of being specified in the Directory Definition message
       (DIRDEF). One occurrence of the message shall contain only one
       MIG. An IMPDEF message for the message being implemented may
       contain:
       
       a. the specification of the implementation usage
       b. additional implementation guidance
       c. presentation and processing guidance
       
       The IMPDEF message shall describe usage of all necessary
       components (segment groups, segments, composite data elements,
       simple data elements and code values) from an identified source
       message, together with additional components (non-coded data
       values or ranges), to effect an implementation of the target
       message. 
       
       The IMPDEF message may describe those components which are not
       used. By default, those components of the source message which
       are not referenced, are not used in the implementation.
       
       The IMPDEF message shall identify the source message upon which
       it is based. This identification may reference the source
       message contained either in a standard directory or in a
       separate DIRDEF message.
       
       The IMPDEF message shall contain a complete MIG or IC and it
       shall not be used for update or maintenance purposes.
       
       The hierarchical nature of both the source and target message
       structure must be preserved in the IMPDEF message. For example,
       this means that segment group information must be located
       immediately after the segment context of the trigger segment is
       established. Similarly, constituent element information must
       immediately follow the establishment of a segment or composite
       context, as must coded or non-coded values their element
       context.
       
       The main body of the MIG is carried by repeated instances of
       the DFN loop. This loop can be used to encapsulate blocks of
       components and place them in any given prevailing context. It
       can also be used to define aliases or constraint blocks. In
       ordinary use, the DFN segment acts as a device to allow the
       logic flow to cycle through the optional segment groups inside
       the DFN-triggered segment group in the correct order to follow
       the hierarchical message structure. The segment groups within
       the DFN-triggered segment group are ordered so as to minimise
       the number of repeats within ordinary use.
       
       The IMPDEF message maintains a context through the use of the
       segment groups within the DFN-triggered segment group. The DFN
       segment provides a means to redefine or re-establish the
       current context. The segment group that follows the DFN segment
       (and its associated FTX segment[s]) determines which context is
       being changed. For example, in normal message hierarchy
       sequence, codes are defined for elements within segments. To
       revert back to the segment context, a DFN segment would be
       followed by an ELU segment; similarly, to change the segment
       context, a DFN segment would be followed by an SGU segment.
       However, components such as repeats, references or
       relationships are considered to be applied in the context at
       which they are defined. Thus repeats, references, relationships
       or data representations may be applied to the whole message,
       individual segments, elements or composites.
       
       When the DFN is used to perform encapsulation, the current
       context is considered to be stacked upon entry, inherited
       within, and restored upon exit. However, any encapsulated block
       may establish its own context at any time, either retaining or
       discarding any or all of the inherited context. Upon exit, the
       previous context is re-established, but may be immediately
       modified, in whole or part, by the components that follow the
       closing DFN segment.
       
       The ordering of the components is governed by the source
       message hierarchy. Whilst the components at any particular
       level may be carried in any order, the message hierarchy must
       be maintained. This means that usage requirements of data
       elements within a segment must follow the usage requirements of
       that segment, but may themselves be presented in any order.
       Similarly, usage requirements of individual segments within a
       segment group must follow the trigger segment and the group
       definition and be presented together, but in any order.
       
       Where constraints are used, and a constraint is active either
       because the constraint expression at the start of the
       constraint is true or because the implicit context of the
       constraint definition is active, then the usage specifications
       inside the constraint block shall prevail against those which
       would apply were the constraint not active. For example, if a
       segment is implicitly 'Not Used' by not being mentioned in the
       main body of the MIG or IC, but is explicitly tagged as
       'Required' within an active constraint, then the prevailing
       usage shall be 'Required'. Conversely, if a segment is
       explicitly used in the main body of the MIG or IC, and also
       explicitly tagged as 'Not Used' within an active constraint
       then the prevailing usage shall be 'Not Used'.
       
       The Interchange header shall specify character set level C.

2.     REFERENCES

       See UNTDID, Part 4, Chapter 2.3 UN/ECE UNSM - General
       Introduction, Section 1.

3.     TERMS AND DEFINITIONS

3.1    Standard terms and definitions

       See UNTDID, Part 4, Chapter 2.3 UN/ECE UNSM - General
       Introduction, Section 2.

3.2    Message terms and definitions

       The following additional definitions are for constituent parts
       of a message whose implementation is being described within an
       IMPDEF message:
       
       Alias: this is used to describe a group of components collected
       together and named for frequent or repetitive use.
       
       Component: this is used in a generic sense to apply to any item
       which may be a part of, or referenced by a part of a MIG. Thus
       it may refer to a segment, a segment group, a simple or
       composite element, a code list or individual code or non-coded
       value. It may also refer to structures such as an alias or a
       constraint within a MIG.
       
       Constraint: this is used to describe a group of components with
       either an explicit or implicit constraint expression, which may
       be named for error reporting and context determination.
       
       Source Message: this is used to refer to the original message
       specification as published in the relevant standard by the
       responsible authority.
       
       Target Message: this is used to refer to the resultant message
       specification produced by applying the restrictions,
       clarifications and constraints contained within the MIG to the
       Source Message.

4.     MESSAGE DEFINITION

4.1    Segment clarification

       This section should be read in conjunction with the segment
       table which indicates mandatory, conditional and repeating
       requirements.

0010   UNH, Message header
       A service segment starting and uniquely identifying a message.
       The message type code for the EDI implementation guide
       definition message is IMPDEF.

       Note: EDI implementation guide definition messages conforming
       to this document must contain the following data in segment
       UNH, composite S009:

       Data element  0065 IMPDEF
                     0052 D
                     0054 01C
                     0051 UN

0020   BGM, Beginning of message
       A segment to indicate the beginning of the message and to
       transmit function, type and number of the message.

0030   MSG, Message type identification
       A segment identifying a message type to which the
       implementation details apply.

0040   RCS, Requirements and conditions
       A segment specifying the distribution conditions for the
       implementation.

0050   DII, Directory identification
       A segment specifying the identity of the source directory set
       and giving its language and maintenance operation. This
       identifies the underlying standard from which the standard
       message is drawn.

0060   RFF, Reference
       A segment carrying reference information for the implementation
       as a whole. This may specify the unique registration identifier
       of this implementation guide; it may carry references to
       graphical information to be used or displayed whenever the
       implementation is physically displayed.

0070   DTM, Date/time/period
       A segment specifying dates related to the implementation guide,
       such as date of issue or date of approval.

0080   FTX, Free text
       A segment providing implementation guide notes which relate to
       the implementation as a whole. It may also carry various legal
       or contractual phrases which may apply to the ownership or
       copyright of the implementation guide, or contractual terms
       which will be incorporated by reference into any contract of
       which a data transmission using this implementation is a part.


0090   Segment group 1:  PNA-ADR-SG2
       A group of segments identifying the parties involved in the
       transaction with associated information. For publicly available
       implementation guides this includes details of the ownership
       and origination of the guide.

0100      PNA, Party identification
          A segment identifying the names of the parties involved in
          the transaction, e.g., originator, requester, author or
          secretariat.

0110      ADR, Address
          A segment identifying the address of the party.


0120      Segment group 2:  CTA-COM
          A group of segments identifying a person or a department and
          identifying communication type and number.

0130         CTA, Contact information
             A segment identifying a person or a department for the
             party to whom the communication should be directed.

0140         COM, Communication contact
             A segment identifying communication type and number of
             the person.


0150   Segment group 3:  DFN-FTX-SG4-SG5-SG6-SG7-SG8-SG9-SG10-SG11-
                         SG12
       A group of segments to describe the usage of a segment, a
       segment group, a composite or an element, an alias, or a
       constraint in a MIG or IC. The iterations of this segment group
       form the bulk of the MIG or IC.
       
       The MIG or IC consists of a series of iterations of this
       segment group which describe the target message hierarchy.
       Within the hierarchy, additional occurrences of this segment
       group may specify the conditions or relationships between the
       components.
       
       Only the appropriate parts of this segment group should be used
       as necessary on any particular iteration. The other contained
       segment groups are ordered to minimise the number of iterations
       of this segment group. The 'Alias' and 'Constraint' instances
       of this segment group provide a mechanism for grouping or
       encapsulating blocks of components. An 'Alias' has no context,
       and therefore takes on the context of the point at which it is
       used. A 'Constraint' inherits the context in which it is
       defined, but may redefine any part of its context by using the
       appropriate optional segment groups within the main segment
       loop. 
       
       As well as its defining function, each component may also be
       used in a constraining manner. For example, a repeating segment
       may not only define its components, but also the number of
       times it is allowed to repeat; then, within each instance, a
       different combination of element requirements may be expressed.
       This conditionality may be based on either ordering or content
       criteria.
       
       Once defined, an 'Alias' may be used throughout the MIG where
       required, by "using" the definition which is identified by its
       'name'. Similarly, in error reporting, an active constraint may
       be identified by its 'name'.

0160      DFN, Definition function
          A segment identifying the object of the definition, and
          containing an optional 'name' or identifier.

0170      FTX, Free text
          A segment providing implementation guide notes pertaining to
          the preceding definition, or to carry the text of a
          constraint expression.


0180      Segment group 4:  GRU-FTX
          A group of segments identifying a segment group and
          providing details about segment group usage. This segment
          group depends on a segment context having been established
          by an instance of a segment group describing segment usage.
          
          This segment group defines a segment group context for the
          target message, and will immediately follow the definition
          of the trigger segment context, preceding the constituent
          elements within the trigger segment.
          
          Several instances of the same segment group may be
          described, with the MEA segment group distinguishing which
          range or instance of the target message segment is being
          described.

0190         GRU, Segment group usage details
             A segment specifying the usage of a segment group in a
             definition. The segment may identify one or more
             instances of a target segment group.

0200         FTX, Free text
             A segment providing implementation guide notes or textual
             information related to the specific group in the
             underlying message.


0210      Segment group 5:  SGU-FTX
          A group of segments specifying segment usage within the
          definition. There will be at least one instance of this
          segment group for each segment described in the
          implementation guide.
          
          This segment group defines a segment context, and all the
          following components are deemed to be within the context of
          the segment whose usage is being defined until a subsequent
          segment context is defined.
          
          Several instances of the same segment may be described, with
          the MEA segment group distinguishing which range or instance
          of the target message segment is being described.

0220         SGU, Segment usage details
             A segment specifying the usage of a segment in a message
             type structure for this definition. As well as defining
             the specific usage of a particular target segment, this
             segment also provides the segment context for the
             following element usage details. The segment may identify
             one or more instances of usage for any particular segment
             in the target data message.

0230         FTX, Free text
             A segment providing implementation guide notes, or
             textual information relating to the specific segment in
             the underlying message.


0240      Segment group 6:  FNT-REL-GIR-FTX
          A group of segments specifying formalised relationships
          among the various components of this implementation at a
          particular context, such as additional rules concerning
          syntax and semantics which are specific to an
          implementation.
          
          The relationships may be both intra-component, such as
          between elements in a segment, or inter-component, such as
          between elements in different segments.
          
          Depending on the context in which this segment group is
          used, it may specify relationships between segments or
          segment groups in a message, between data elements in a
          segment, or between data elements in a composite.

0250         FNT, Footnote
             A segment specifying a footnote identification number
             that may place the relationship in the current context.

0260         REL, Relationship
             A segment specifying a relationship between the various
             components, typically data elements in a segment, in the
             current context.

0270         GIR, Related identification numbers
             A segment identifying the various components in a
             relationship, typically data elements in a segment, in
             the current context.

0280         FTX, Free text
             A segment carrying text notes to the preceding
             relationship.


0290      Segment group 7:  RFF-FTX
          A group of segments carrying references, or constraints
          whose default context applies to the containing segment.
          This segment group may be used to change the constraint
          mechanism at the current and deeper levels in the message
          hierarchy. Additionally, this segment group may be used to
          carry legal and contractual terms which relate, either by
          way of explanation or to be incorporated by reference, in
          the particular context at which the group appears.
          
          Depending on the context, the references may be applied to
          the target message as a whole, the current segment or
          element context, or the current code value context.

0300         RFF, Reference
             A segment identifying a reference document or a following
             constraint expression.

0310         FTX, Free text
             A segment carrying the text of a constraint expression or
             providing implementation guide notes pertaining to the
             preceding constraint.


0320      Segment group 8:  ELU-ELM-EDT-IMD-GIS-FTX
          A group of segments specifying implementation requirements
          for data elements in the current segment or composite
          context. Multiple instances of this segment group will
          typically be used to describe the usage of all the elements
          in any given segment or composite context. There will be at
          least one instance of this segment group for each element
          used, although a constraint structure may override or
          further define the specification in any particular context
          or sub-context. The MEA segment group may be used to provide
          repeat range or specific instance information for repeating
          data elements.
          
          This segment group defines an element or composite context
          which will remain in force until the next element or
          composite context is defined, or a new segment context is
          established.

0330         ELU, Data element usage details
             A segment identifying the usage of a simple or composite
             data element in the current context. This segment starts
             a block of information about any one particular
             contextualised usage of a data element in a target data
             message.
             
             The data element usage determines whether this segment is
             defining a composite context, a simple element context or
             a component element context.

0340         ELM, Simple data element details
             A segment providing details of any variation or
             restriction of the current data element as used in this
             context. Typically this segment will convey details of
             restricted size or character representation.

0350         EDT, Editing details
             A segment providing details of any editing information
             such as maximum field length and status that would be
             used by a screen-based editor, forms input or data output
             process when physical representation of the data carried
             in a data message using this implementation guide is
             required.

0360         IMD, Item description
             A segment providing further details of presentational
             information such as text alignment and style that might
             be used by a screen-based editor, forms input or data
             output process when physical representation of the data
             carried in a data message using this implementation guide
             is required.

0370 X       GIS, General indicator
             A segment providing further details of processing
             information such as data handling, positioning or control
             that might be used by a screen-based editor, forms input
             or data output process when data is carried, stored or
             collected by a data message using this implementation
             guide is required.

0380         FTX, Free text
             A segment providing implementation guide notes, or other
             textual information relating to this element usage. The
             segment will also be used to carry the final set of
             information that would be used by a screen-based editor;
             forms input or data output process; a legend or user-
             recognisable description; and a help text.


0390      Segment group 9:  MEA-FTX
          A group of segments specifying implementation requirements
          for the number of instances of repeating segments, segment
          groups or elements in the current context. Multiple
          instances of this segment group will typically be used to
          describe both the overall limits of usage and to identify
          individual instances in any given context.

0400         MEA, Measurements
             A segment to measure the number of instances of usage of
             a component in a message. The segment may specify minima,
             maxima, range or instance criteria.

0410         FTX, Free text
             A segment providing implementation guide notes, or other
             textual information relating to this measurement.


0420      Segment group 10: ELV-FTX
          A group of segments specifying the usage of values for a
          non-coded data element. Multiple instances of this segment
          group may be used to provide a complete set of ranges or
          specific values, including preferences. It can be used for
          any other type of data element, such as strings, numerics,
          dates and times. It can also specify a default value and
          associated implementation notes for a specific element in a
          particular context. 
          
          A simple element or component element context must have been
          established before this segment group is used.

0430         ELV, Element value definition
             A segment identifying one or more components of an
             element value constraint series. It also may provide a
             default value for the current element context. This is
             expressed in a single text field so as to be used by or
             applicable to the broadest range of applications.

0440         FTX, Free text
             A segment providing implementation guide notes, or other
             textual information related to the particular context.
             Such a context may include implementation guide notes for
             the default value.


0450      Segment group 11: CDV-FTX
          A group of segments specifying the usage of code values for
          a coded data element. Multiple instances of this segment
          group may be used to provide a complete set of code values,
          including preferences.
          
          A simple element or component element context must have been
          established before this segment group is used.

0460         CDV, Code value definition
             A segment identifying the code value, its source and
             usage preference.

0470         FTX, Free text
             A segment providing implementation guide notes, or other
             textual information related to the particular context.


0480      Segment group 12: DRD-FTX
          A group of segments specifying data representation details
          for a component of the message. This segment group may be
          used in a segment, group, composite or simple data element
          context to describe the data representation that the
          implementation guide author intends to use to hold, store or
          represent the structure or data in a non-EDI environment.

0490         DRD, Data representation details
             A segment identifying an underlying data representation
             by tag, basic data type and size. This is the
             representation itself, and not a pointer to an external
             document.

0500         FTX, Free text
             A segment providing implementation guide notes, or other
             relevant textual information.


0510   Segment group 13: AUT-DTM
       A group of segments to provide authentication for the message.

0520      AUT, Authentication result
          A segment specifying the details of any authentication
          (validation) procedure applied to the IMPDEF message.

0530      DTM, Date/time/period
          A segment specifying the date of authentication.

0540   UNT, Message trailer
       A service segment ending a message, giving the total number of
       segments in the message (including the UNH & UNT) and the
       control reference number of the message.

4.2    Segment index (alphabetical sequence by tag)

          ADR Address
          AUT Authentication result
          BGM Beginning of message
          CDV Code value definition
          COM Communication contact
          CTA Contact information
          DFN Definition function
          DII Directory identification
          DRD Data representation details
          DTM Date/time/period
          EDT Editing details
          ELM Simple data element details
          ELU Data element usage details
          ELV Element value definition
          FNT Footnote
          FTX Free text
          GIR Related identification numbers
       X  GIS General indicator
          GRU Segment group usage details
          IMD Item description
          MEA Measurements
          MSG Message type identification
          PNA Party identification
          RCS Requirements and conditions
          REL Relationship
          RFF Reference
          SGU Segment usage details
          UNH Message header
          UNT Message trailer

4.3 Message structure 4.3.1 Segment table Pos Tag Name S R 0010 UNH Message header M 1 0020 BGM Beginning of message M 1 0030 MSG Message type identification M 1 0040 RCS Requirements and conditions C 1 0050 DII Directory identification M 1 0060 RFF Reference C 99 0070 DTM Date/time/period C 9 0080 FTX Free text C 999 0090 ----- Segment group 1 ------------------ C 5-----------+ 0100 PNA Party identification M 1 | 0110 ADR Address C 1 | | 0120 ----- Segment group 2 ------------------ C 9999-------+| 0130 CTA Contact information M 1 || 0140 COM Communication contact C 5----------++ 0150 ----- Segment group 3 ------------------ C 99999-------+ 0160 DFN Definition function M 1 | 0170 FTX Free text C 99 | | 0180 ----- Segment group 4 ------------------ C 1----------+| 0190 GRU Segment group usage details M 1 || 0200 FTX Free text C 99---------+| | 0210 ----- Segment group 5 ------------------ C 999--------+| 0220 SGU Segment usage details M 1 || 0230 FTX Free text C 99---------+| | 0240 ----- Segment group 6 ------------------ C 99---------+| 0250 FNT Footnote M 1 || 0260 REL Relationship C 1 || 0270 GIR Related identification numbers C 9 || 0280 FTX Free text C 99---------+| | 0290 ----- Segment group 7 ------------------ C 99---------+| 0300 RFF Reference M 1 || 0310 FTX Free text C 99---------+| | 0320 ----- Segment group 8 ------------------ C 99---------+| 0330 ELU Data element usage details M 1 || 0340 ELM Simple data element details C 1 || 0350 EDT Editing details C 1 || 0360 IMD Item description C 9 || 0370 X GIS General indicator C 9 || 0380 FTX Free text C 99---------+| | 0390 ----- Segment group 9 ------------------ C 999--------+| 0400 MEA Measurements M 1 || 0410 FTX Free text C 99---------+| | 0420 ----- Segment group 10 ------------------ C 99999------+| 0430 ELV Element value definition M 1 || 0440 FTX Free text C 99---------+| | 0450 ----- Segment group 11 ------------------ C 99999------+| 0460 CDV Code value definition M 1 || 0470 FTX Free text C 99---------+| | 0480 ----- Segment group 12 ------------------ C 99999------+| 0490 DRD Data representation details M 1 || 0500 FTX Free text C 99---------++ 0510 ----- Segment group 13 ------------------ C 1-----------+ 0520 AUT Authentication result M 1 | 0530 DTM Date/time/period C 1-----------+ 0540 UNT Message trailer M 1

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