ISO 8583:1987 response code

1A

Reserved for ISO use

Standard version: ISO 8583:1987
Paired version code: No direct pair assigned

In ISO 8583:1987, response code 1A means “Reserved for ISO use”. The reviewed dataset contains entries for Visa and Discover; 3 of the five scheme columns remain N/A.

Merchant handling

Actions to be taken

Do not infer a merchant action from this reserved value. Use the exact acquirer or processor specification that assigned the code before continuing the transaction.

This is conservative merchant guidance derived from the published response meaning. Current scheme, acquirer, processor, merchant advice, and transaction-specific rules take precedence.

Scheme comparison

Descriptions in the reviewed sources

Each populated value links to its scheme record and preserves the raw code published by that source. N/A means no matching description exists in the reviewed public dataset.

Scheme descriptions compared with ISO 8583:1987 response code 1A
Scheme	Raw code	Source description	Evidence
Visa	1A	Additional customer authentication required	Official
Mastercard	N/A	N/A	N/A
American Express	N/A	N/A	N/A
Discover	1A	Customer authentication required	Secondary source
UnionPay	N/A	N/A	N/A

Standard sources

Version and response-name evidence

ISO 8583:1987 metadataOfficial edition metadata; the full value table is not public.
ISO
Wikipedia ISO 8583 version tablesSecondary public source for the displayed response name.
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