All the records contain an initial field serving the uniquely identify them, and to note the type of record it is.
It should be noted that the prefix structure on this page applies only to Transaction and Detail records. Control records lack the Transaction Sequence Number and the Record Sequence Number.
This field is the record prefix, which contains just three values:
| Field | Type | Description |
|---|---|---|
| Record Type | Table Lookup | One from the Record Type or Transaction Type tables |
| Transaction Sequence # | Numeric | Unique ID for each Transaction in a Group |
| Record Sequence # | Numeric | Unique ID for each Detail Record in a transaction |
Transactions and Detail Records share both sequence numbers, but use them in a different way.
Transactions have the Record Sequence Number set to 0 always. Their Transaction Sequence Number is 0 for the first Transaction on a Group, and a consecutive value for the following Transactions on the same Group.
Detail Records use the Transaction Sequence Number of the Transaction they are part of, while the Record Sequence Number is that of the previous Record plus one.
Ambiguity: the specification file is not very clear about the Detail
Records numbering. I suppose the first Detail Record on a Transaction
should have RSN 1 (RSN of the Transaction, which is 0, plus 1)
This would be an example of sequence numbering:
| Record Type | Transaction Sequence # | Record Sequence # |
|---|---|---|
| First transaction header | 0 | 0 |
| First detail in transaction | 0 | 1 |
| Second detail in transaction | 0 | 2 |
| Third detail in transaction | 0 | 3 |
| Second transaction header | 1 | 0 |
| First detail in transaction | 1 | 1 |
| Second detail in transaction | 1 | 2 |
| Third transaction header | 2 | 0 |
| First detail in transaction | 2 | 1 |
| Second detail in transaction | 2 | 2 |
| Third detail in transaction | 2 | 3 |
| Fourth detail in transaction | 2 | 4 |