Section title: Requests for Interpretation
835 - ST02 Data Element Type

Clarification is needed on the format structure, specifically character usage, of the ST02 data element in the electronic remittance advice (835) that can be sent to trading partners. Can alpha characters, numeric characters, special characters or a combination thereof be sent in the ST02?
Page 68 of the TR3 specification shows the ST02 having a data element attribute of AN.
On page B.7 of the appendix, the symbol AN is a data element type of String.
Section B. of the 835 TR3 further clarifies the meaning of a string. A string data element is a sequence of any characters from the basic or extended character sets.
Page B.3 of the appendix, section B. identifies the basic character set values. Section B. identifies the extended character set values.


The submitter indicates that their reference is an 005010 Type 3 Technical Report (TR3) for transaction set 835. A TR3 is synonymous with implementation guide. Portions of the base X12 standard are paraphrased in TR3s, but the request is really about the base standard. The following 005010 X12 standards were reviewed in developing this interpretation:
- X12.22 Segment Directory
- X12.3 Data Element Dictionary
- X12.6 Application Control Structure

X12.22 states that the second data element in the ST segment, represented as ST02, is data element 329.
X12.3 states for the physical attributes of DE 329 that the data element is an AN type with this definition: "Identifying control number that must be unique within the transaction set functional group assigned by the originator for a transaction set."
X12.6 states in section that the AN symbol represents a string. In section, a string is in part defined as: "A string data element is a sequence of any characters from the basic or extended character sets and contains at least one non-space character." Section 3.3.1 states: "The basic character set of this standard consists of uppercase letters, digits, special characters, and space." Section 3.3.2 states: "An extended character set may be used by agreement between communicating parties and includes the lowercase letters, other special characters, national characters, and select language characters, and other language characters."
Aside from the constraint concerning uniqueness over time for ST02 values and the range constraint implicit in the type and length attributes of data element 329, the standard places no other constraints on ST02 values.


The uniqueness constraint on ST02 values supports the identification of a specific transaction set within a functional group when reporting in a functional acknowledgement the results of a syntactic analysis of a transmitted functional group. The value of an ST02 instance is established by the sender of the transaction set, in accordance with the rules set forth in the X12 standards
As with all details of the X12 standards, implementation guides and trading partner agreements may impose additional constraints upon syntax. For example, an implementation guide could impose a constraint that each functional group start a new sequence of ST02 values starting with the number '0001' and incrementing by '1'. In the absence of such additional constraints, the creator of an X12 functional group need only adhere to the constraints specified in the X12 standards.

The referenced TR3 contains a note on ST02: "The Transaction Set Control Numbers in ST02 and SE02 must be identical. This unique number also aids in error resolution research. Start with a number, for example 0001, and increment from there. This number must be unique within a specific group and interchange, but it can be repeated in other groups and interchanges." The note states 'number,' in other words a numeric value, as opposed to 'value,' in other words alphabetic or numeric, and provides a numeric example for creating uniqueness. The intent of the 005010 TR3 element note establishes it as a number or numeric value that must be unique within the group and interchange.