The Basics
"X12" is the short name for the ANSI ASC X12 standard. ANSI stands for "American National Standards Institute." ASC stands for Accredited Standards Committee. X12 is the designation of the committee. The X12 standard is considered to be the primary standard for North American trade using EDI.
X12 refers to the documents exchanged as " Transaction sets. " Message structures are made up of " segments " and " loops." X12 data within a message, must appear in the order presented in the message structure definition.
Versions
X12 releases new versions of messages, segments, and elements in "releases" and "sub-releases"
The naming structure is as follows: vvvrrr where vvv represents the version number and rrr represents the release and sub-release. Here are a couple of examples:
003010 represents version 3, release 1, sub-release 0.
003072 repserents version 3, release 7, sub-release 2.
Before release 002040, the naming convention was similar, however since there were no sub-releases, the full rrr was used for the release level. So, as an example, 002002 represents version 2, release 2.
It is pretty common to omit the leading zeros when referring to an X12 release. For example, 004010 is usually refered to as simply 004010.
Enveloping and Transmission Structures
X12 data is transmitted in packages referred to as interchanges.� The interchange is the outermost layer of a hierarchical grouping of data.� Each of the major layers is bounded by special segments known as envelope segments.� Here is the relation of the different enveloping segments used in X12 transmissions:
ISA (interchange header) ------------+
GS (functional group header) ----------+ |
ST (transaction set header) --------+ | |
<transaction set data> ??????? | | |
SE (transaction set trailer) --------+ | |
GE (functional group trailer) ----------+ |
IEA (interchange trailer) ------------+
All of the enveloping structure segments are required. If there are multiple transaction sets of the same type, they can be sent within the same functional group. There may be multiple functional groups within a single interchange.
More information on the structure and usage of envelopes in X12 is available in most X12 manuals (we always recommend the latest release).
Default Separator Characters
In X12, most non-alphabetic, non-numeric characters can be used as separator characters. The separator characters used within a given interchange are determined by the characters used in the ISA segment. This is based on the assumption that the ISA is a fixed length segment because it contains only fixed length, mandatory fields. By comparing the fixed positions for the separators (based on the lengths of the fields) it is possible to establish the existence of an ISA segment in a data stream and determine what separator characters have been selected for use within. Unlike EDIFACT, the standard makes no provision for a release character. Therefore, separator characters must never be used as data characters.
Last updated: 05-27-2005 19:39:11
