B.1 ASC X12 Nomenclature

NOTE: THIS PAGE IS NOT THE COMPLETE APPENDIX. IT IS A SAMPLE USED IN CONJUNCTION WITH THE WPC CHANGE DESCRIPTION IMPLEMENTATION GUIDES

B.1.1 Interchange and Application Control Structures

Appendix B is provided as a reference to the X12 syntax, usage, and related information. It is not a full statement of Interchange and Control Structure rules. The full X12 Interchange and Control Structures and other rules (X12.5, X12.6, X12.59, X12 dictionaries, other X12 standards and official documents) apply unless specifically modified in the detailed instructions of this implementation guide (see Section B.1.1.3.1.2 - Decimal for an example of such a modification).

B.1.1.1 Interchange Control Structure

The transmission of data proceeds according to very strict format rules to ensure the integrity and maintain the efficiency of the interchange. Each business grouping of data is called a transaction set. For instance, a group of benefit enrollments sent from a sponsor to a payer is considered a transaction set.

Each transaction set contains groups of logically related data in units called segments. For instance, the N4 segment used in the transaction set conveys the city, state, ZIP Code, and other geographic information. A transaction set contains multiple segments, so the addresses of the different parties, for example, can be conveyed from one computer to the other. An analogy would be that the transaction set is like a freight train; the segments are like the train's cars; and each segment can contain several data elements the same as a train car can hold multiple crates.

The sequence of the elements within one segment is specified by the ASC X12 standard as well as the sequence of segments in the transaction set. In a more conventional computing environment, the segments would be equivalent to records, and the elements equivalent to fields.

Similar transaction sets, called "functional groups," can be sent together within a transmission. Each functional group is prefaced by a group start segment; and a functional group is terminated by a group end segment. One or more functional groups are prefaced by an interchange header and followed by an interchange trailer. Figure B.1 - Transmission Control Schematic, illustrates this interchange control.

Figure B.1 - Transmission Control Schematic

The interchange header and trailer segments envelop one or more functional groups or interchange-related control segments and perform the following functions:

Define the data element separators and the data segment terminator.
Identify the sender and receiver.
Provide control information for the interchange.
Allow for authorization and security information.

B.1.1.2 Application Control Structure Definitions and Concepts

B.1.1.2.1 Basic Structure

A data element corresponds to a data field in data processing terminology. A data segment corresponds to a record in data processing terminology. The data segment begins with a segment ID and contains related data elements. A control segment has the same structure as a data segment; the distinction is in the use. The data segment is used primarily to convey user information, but the control segment is used primarily to convey control information and to group data segments.

B.1.1.2.2 Basic Character Set

The section that follows is designed to have representation in the common character code schemes of EBCDIC, ASCII, and CCITT International Alphabet 5. The ASC X12 standards are graphic-character-oriented; therefore, common character encoding schemes other than those specified herein may be used as long as a common mapping is available. Because the graphic characters have an implied mapping across character code schemes, those bit patterns are not provided here.

The basic character set of this standard, shown in Table B.1 - Basic Character Set, includes those selected from the uppercase letters, digits, space, and special characters as specified below.

Table B.1 - Basic Character Set

A...Z	0...9	!	“	&	’	(	)	+	*
,	-	.	/	:	;	?	=	(space)

B.1.1.2.3 Extended Character Set

An extended character set may be used by negotiation between the two parties and includes the lowercase letters and other special characters as specified in Table B.2 - Extended Character Set.

Table B.2 - Extended Character Set

a...z	%	~	@	[	]	_	{
}		\|	<	>	#	$

Note that the extended characters include several character codes that have multiple graphical representations for a specific bit pattern. The complete list appears in other standards such as CCITT S.5. Use of the USA graphics for these codes presents no problem unless data is exchanged with an international partner. Other problems, such as the translation of item descriptions from English to French, arise when exchanging data with an international partner, but minimizing the use of codes with multiple graphics eliminates one of the more obvious problems.

For implementations compliant with this guide, either the entire extended character set must be acceptable, or the entire extended character set must not be used. In the absence of a specific trading partner agreement to the contrary, trading partners will assume that the extended character set is acceptable. Use of the extended character set allows the use of the "@" character in email addresses within the PER segment. Users should note that characters in the extended character set, as well as the basic character set, may be used as delimiters only when they do not occur in the data as stated in Section B.1.1.2.4.1 - Base Control Set.

NOTE: THIS PAGE IS NOT THE COMPLETE APPENDIX. IT IS A SAMPLE USED IN CONJUNCTION WITH THE WPC CHANGE DESCRIPTION IMPLEMENTATION GUIDES. A CONSIDERABLE AMOUNT OF MATERIAL IS MISSING WITHIN THIS AREA.

B.1.1.3.1 Data Element

The data element is the smallest named unit of information in the ASC X12 standard. Data elements are identified as either simple or component. A data element that occurs as an ordinally positioned member of a composite data structure is identified as a component data element. A data element that occurs in a segment outside the defined boundaries of a composite data structure is identified as a simple data element. The distinction between simple and component data elements is strictly a matter of context because a data element can be used in either capacity.

Data elements are assigned a unique reference number. Each data element has a name, description, type, minimum length, and maximum length. For ID type data elements, this guide provides the applicable ASC X12 code values and their descriptions or references where the valid code list can be obtained.

A simple data element within a segment may have an attribute indicating that it may occur once or a specific number of times more than once. The number of permitted repeats are defined as an attribute in the individual segment where the repeated data element occurs.

Each data element is assigned a minimum and maximum length. The length of the data element value is the number of character positions used except as noted for numeric, decimal, and binary elements.

The data element minimum and maximum lengths may be restricted in this implementation guide for a compliant implementation. Such restrictions may occur by virtue of the allowed qualifier for the data element or by specific instructions regarding length or format as stated in this implementation guide.

B.1.1.3.9 Condition Designator

This section provides information about X12 standard conditions designators. It is provided so that users will have information about the general standard. Implementation guides may impose other conditions designators. See implementation guide section 2.1 Presentation Examples for detailed information about the implementation guide Industry Usage requirements for compliant implementation.

Data element conditions are of three types: mandatory, optional, and relational. They define the circumstances under which a data element may be required to be present or not present in a particular segment.

Table B.7 - Condition Designator

DESIGNATOR	DESCRIPTION
M- Mandatory	The designation of mandatory is absolute in the sense that there is no dependency on other data elements. This designation may apply to either simple data elements or composite data structures. If the designation applies to a composite data structure, then at least one value of a component data element in that composite data structure shall be included in the data segment.
O- Optional	The designation of optional means that there is no requirement for a simple data element or composite data structure to be present in the segment. The presence of a value for a simple data element or the presence of value for any of the component data elements of a composite data structure is at the option of the sender.
X- Relational	Relational conditions may exist among two or more simple data elements within the same data segment based on the presence or absence of one of those data elements (presence means a data element must not be empty). Relational conditions are specified by a condition code (see table below) and the reference designators of the affected data elements. A data element may be subject to more than one relational condition.
	The definitions for each of the condition codes used within syntax notes are detailed below:
	CONDITION CODE	DEFINITION
	P- Paired or Multiple	If any element specified in the relational condition is present, then all of the elements specified must be present.
	R- Required	At least one of the elements specified in the condition must be present.
	E- Exclusion	Not more than one of the elements specified in the condition may be present.
	C- Conditional	If the first element specified in the condition is present, then all other elements must be present. However, any or all of the elements not specified as the first element in the condition may appear without requiring that the first element be present. The order of the elements in the condition does not have to be the same as the order of the data elements in the data segment.
	L- List Conditional	If the first element specified in the condition is present, then at least one of the remaining elements must be present. However, any or all of the elements not specified as the first element in the condition may appear without requiring that the first element be present. The order of the elements in the condition does not have to be the same as the order of the data elements in the data segment.