6.2.1 Variable length data elements
For any variable length data element with a maximum length of less than 100 characters, two additional numeric positions shall prefix the data element and shall give its length. The format shall be LLVAR. For any variable length data element with a maximum length of less than 1 000 characters, three additional numeric positions shall prefix the data element and shall give its length. The format shall be LLLVAR. For any variable length data element with a maximum length of less than 10 000 characters, four additional numeric positions shall prefix the data element and shall give its length. The format shall be LLLLVAR.
None of the definitions of variable length data element in this part of ISO 8583 include the two, three or four numeric positions of length in the representation column in Table 2 or Annex B. All length attributes shall be right justified and zero filled, e.g. primary account number 123456789012 is represented by 12123456789012.
The first “12” indicates 12 digits to follow.
6.2.2 Binary data
6.2.2.1 Binary data elements
Binary data elements shall be grouped into blocks of 8 bits. The length attribute defines the number of such blocks present, e.g. the personal identification number data element has an attribute “b 8”, i.e. 8 times 8 bits giving 64 bits of data. In all “b” data elements, blocks of 8 bits are assumed to be left justified with trailing zeroes.
6.2.2.2 Variable length attributes and binary data elements
If the format indicates a numeric variable length attribute in the first two, three or four positions for a binary data element (i.e. LLVAR, LLLVAR or LLLLVAR), the numeric length value contains the number of 8 bit blocks of the binary data element which follows.
Annex C gives guidance on how messages formatted in accordance with this part of ISO 8583 may be transmitted across data networks.
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6.2.3 Expression of amounts
The amount is a numeric value, expressed without a decimal separator. Where a minor unit of currency applies, the relevant minor unit data element indicates the number of decimal places in the relevant amount.
For example, an amount value of 100 in US currency would have a minor currency unit of 2 (e.g. one US dollar), but an amount of 100 in Italian currency would have a minor unit of currency of 0 (e.g. 100 lire).
The value shall be expressed in the currency of the associated currency code data element. Where there is no associated currency code data element, the currency is that of Amount transaction.
A number of amount data elements have an associated sign C for credit and D for debit, such data elements have a representation of “xn” in Table 3, the associated notes and Annex B (see also Table 1). Where such a sign is present, it shall precede the amount. Thus, an amount which is 16 digits long is actually 17 digits with the sign in the leftmost position.
6.2.4 Conversion rates
In conversion rate data elements, the leftmost digit denotes the number of positions the decimal separator shall be moved from the right. Position 2-8 is the rate, e.g. a conversion rate value of 91234567 would equate to 0.001234567. The maximum number of digits to the right of the decimal separator is 9. If the value of the first digit is 8, a single zero after the decimal point is assumed. If the value of the first digit is 9, two zeroes after the decimal point are assumed.
6.2.5 Identification of institutions and routing 6.2.5.1 General
Card issuing institutions shall be identified by the procedure specified in ISO 7812-1. Institutions that are not card issuers shall be identified by a six-digit code as defined in Clause 10.
A transaction may be sent from an acquirer to a card issuer, from a card issuer to an acquirer or from a transaction originator to a transaction destination. However, in the routing of a transaction between these pairs of institutions, other institutions may need to handle the transaction. The data elements Forwarding institution identification code and Receiving institution identification code facilitate this routing activity. The Acquiring institution identification code and Primary account number PAN data elements contain the same data for the life of the transaction. Where the Transaction originator identification code and Transaction destination identification code are used, they contain the same data for the life of the transaction. The contents of the Forwarding institution identification code and Receiving institution identification code data elements will change as the transaction is sent between institutions.
Tables 4 to 6 and Figures 6 to 8 below show how the institution identifiers are used when the acquirer and the card issuer cannot communicate directly. Where direct communication is possible, the Forwarding institution identification code and Receiving institution identification code data elements shall not be used.
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6.2.5.2 Acquirer to card issuer
In a transaction from an acquirer to a card issuer, the contents of the relevant institution identifier data elements are indicated in Table 4 and graphically in Figure 6. The letters A and B represent other institutions that may be present between acquirers and card issuers. The Authorizing agent institution identification code data element shall be used in the response message to indicate where an agent stands in for the card issuer.
This data element is not shown, as it is not used for routing.
Table 4 — Usage of institution identification codes in acquirer generated messages In request, advice or notification messages
Institution Bit Acquirer to A A to B B to Card issuer
Acquirer 32 Remains the same throughout the transaction.
Forwarding institution 33 a A B
Receiving institution 100 A B b
Card issuer 2 Remains the same throughout the transaction.
In response messages
Institution Bit Card issuer to B B to A A to Acquirer
Acquirer 32 Remains the same throughout the transaction.
Forwarding institution 33 b B A
Receiving institution 100 B A a
Card issuer 2 Remains the same throughout the transaction.
a Not used when the forwarding or receiving institution is the acquirer.
b Not used when the receiving or forwarding institution is the card issuer.
Figure 6 — Usage of institution identification codes in acquirer generated messages
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6.2.5.3 Card issuer to acquirer
In a transaction from a card issuer to an acquirer, the contents of the relevant institution identifier data elements are indicated in Table 5 and graphically in Figure 7. The letters A and B represent other institutions that may be present between card issuers and acquirers.
Table 5 — Usage of institution identification codes in card issuer generated messages In request, advice notification or instruction messages
Institution Bit Card issuer to A A to B B to Acquirer Card issuer 2 Remains the same throughout the transaction.
Forwarding institution 33 a A B
Receiving institution 100 A B b
Acquirer 32 Remains the same throughout the transaction.
In response messages
Institution Bit Acquirer to B B to A A to Card issuer Card issuer 2 Remains the same throughout the transaction.
Forwarding institution 33 b B A
Receiving institution 100 B A a
Acquirer 32 Remains the same throughout the transaction.
a Not used when the forwarding or receiving institution is the card issuer.
b Not used when the receiving or forwarding institution is the acquirer.
Figure 7 — Usage of institution identification codes in card issuer generated messages
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6.2.5.4 Transaction originator to transaction destination
In a transaction from a transaction originator to a transaction destination, the contents of the relevant institution identifier data elements are indicated in Table 6 and graphically in Figure 8. The letters A and B represent other institutions that may be present between the transaction originator and transaction destination.
Table 6 — Usage of institution identification codes in transaction originator generated messages In request, advice notification or instruction messages
Institution Bit Originator to A A to B B to Destination Transaction originator 94 Remains the same throughout the transaction.
Forwarding institution 33 a A B
Receiving institution 100 A B b
Transaction destination 93 Remains the same throughout the transaction.
In response messages
Institution Bit Destination to B B to A A to Originator Transaction originator 94 Remains the same throughout the transaction.
Forwarding institution 33 b B A
Receiving institution 100 B A a
Transaction destination 93 Remains the same throughout the transaction.
a Not used when the forwarding or receiving institution is the transaction originator.
b Not used when the receiving or forwarding institution is the transaction destination.
Figure 8 — Usage of institution identification codes in transaction originator generated messages
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6.2.6 Identification of account numbers
The Primary account number (PAN) shall contain the account number used to identify a customer account or relationship and shall remain unchanged for the life of a transaction.
The following data elements shall be used to identify specific accounts held by the cardholder at the card issuer and, if present, they shall remain unchanged for the life of a transaction:
a) Account identification 1;
b) Account identification 2.
6.2.7 Tag length value (TLV) data
Within a number of data elements, there is a provision made for data to be encoded in TLV format. This part of ISO 8583 follows the conventions defined in ISO 7816-4 in the creation of values. Tag values specific to this part of ISO 8583 are referenced in the relevant clauses and listed together in Clause A.18.