4.1.1 Layout of data element entries The first line of each data element entry contains the numeric tag and the name of the data element and indicates if the data element is found in the United Nations Trade Data Interchange Directory (UNTDID) noted "E" (see section 1.8).
In addition, and in accordance with the principles set out in section 1.6, each data element entry contains a number of parts, identified by a header. The following headers are used to designate the different parts of the entries:
| a) "Desc" | = | description of the data element |
| b) "Repr" | = | character representation, space available and location of the data entry, as explained below |
| c) "Note" | = | additional information, when appropriate |
| d) "Ref" | = | reference to an indicated source of information in cases where a "Note" is not sufficient. (Reference to other sections in the Directory is normally indicated by "cf" and the section number.) |
| e) "Syn" | = | synonyms for the data element name |
Data element entries are separated from each other by a line. Data elements with directly related clear text (even tag number) and coded (the next odd number) value representations appears one after the other.
| a | = | alphabetic characters |
| n | = | numeric characters |
| an | = | alphabetic and numeric characters |
| 3 | = | fixed length of 3 characters |
| ..17 | = | variable data unit size where "17" indicates the maximum number of available character positions; |
| ..35x5 | = | undefined length where space is available to accommodate up to 5 lines of 35 characters each; |
| ..35xn | = | undefined length where the data item requires an undefined number of lines of up to 35 characters each |
| an5 (aannn) | = | fixed length of 5 alphanumeric characters, with 2 alphabetic characters to be followed by 3 numeric digits, in that order, without separation |
| an5 (aa-nn) | = | fixed length of 5 alphanumeric characters, composed of two sub-elements as shown, with mandatory separation by hyphen( - ) |
| n7 (nn,nnnn,n) | = | fixed length of 7 numeric digits, composed of three sub-elements as shown, without mandatory separation; the comma ( , ) indicates the division between the sub-elements |
| (n2) a3 | fixed length of 3 alphabetic characters, to be preceded by another data element of 2 numeric digits; | |
| L | = | line, to be followed by the line number (or numbers) for the data entry according to ISO 3535 and the UNLK |
| P | = | position, to be followed by the character position number (or numbers) for the data entry according to ISO 3535 and UNLK |
Whenever line and character positions are given for data elements appearing in internationally-established, aligned forms, this is done with a view either to confirm conformity to the UNLK, or to indicate deviations from the UNLK, or differences between such forms.
If fixed field lengths have been specified in a particular interchange protocol, this will be shown after an acronym, e.g. SWIFT: n6, CIMP: an..12, UNSM: an5. This is done mainly to indicate possible constraints for data items likely to be transmitted through such systems. In some instances organizations have introduced sectoral codes other than those recommended within ECE. Such cases are indicated by reference to the relevant organization or Convention, e.g. currency code in Rail Consignment Note: CIM n2.
The following acronyms or abbreviations used for making reference to documents, conventions and interchange standards are listed in section 1.4.
In specifications of character representation and entry location in
aligned forms, these acronyms are used as follows:
a) Representation and location unique for AWB:
b) Representation and location in AWB deviates from general
UNLK-based standard:
c) Representation in AWB and CMR follows general standard but location is specific for each document:
d) Representation in AWB follows general standard but differs
in CIM:
The following grouping is used in the Directory:
The system selected for the Directory for grouping data elements into broad categories is based on the characteristics of the data item, taking into account its nature rather than its application area. This means that all dates are placed in one group, all names in another, and all amounts in a third, without any consideration of the kind of date, name and amount.
Users, even if they do not know the exact name of a data element, or in which application area a particular data element might have been placed, are likely to know the expected contents of the data item with sufficient accuracy to be able to find it within a limited range of not more than one hundred data elements placed together according to this principle.
Attention is drawn to the allocation of tag numbers in each category. Up to 799 are reserved for allocation by the UNTDED secretariat. Within UN/EDIFACT, tags up to 699 are used for data elements in the UNSM (Status 2) and TRIAL (Status 1) message types while 700 to 799 are used in message types under development. Tags from 800 upwards are for free use.