Common Header

Every VAVS message contains a common header and an operation-specific body. Offsets below are zero-based offsets within the 200-byte VAVS message, excluding the transport Length header.

NOTE

TCP Frame Offsets

The actual TCP frame adds a separate four-byte transport Length header (0200) before the VAVS message. Add four to each offset below to obtain the TCP-frame offset. For example, the institution code is at message offset 4 and TCP-frame offset 8.

Fields

No.	Field	MODE	Length	Offset	Request	Response	Description
1	LENGTH	N	4	0	●	○	Complete VAVS message length including this common-header LENGTH field; fixed to `0200`
2	Institution code	AN	8	4	●	○	Assigned by Hecto Financial
3	Transaction type	N	4	12	●	⊙	Operation request or response code
4	Direction code	N	1	16	●	⊙	Sender and receiver direction
5	Transaction date	N	8	17	●	○	`YYYYMMDD`
6	Transaction time	N	6	25	●	⊙	`HHMMSS`
7	Legacy opening-bank code	AN	2	31	●	○	Two-digit bank code
8	Transaction number	AN	7	33	●	○	Hecto Financial transaction sequence
9	Response code	AN	4	40	●	⊙	Processing result
10	Opening-bank code	AN	3	44	●	○	Three-digit financial institution code
11	Reserved 1	AN	4	47	●	○	VAVS reserved
12	Reserved 2	AN	7	51	●	○	VAVS reserved
13	User transaction number	N	7	58	-	-	Daily unique number generated by the client
14	Origin code	AN	1	65	●	○	Original transaction source
15	Delivery mode	A	1	66	●	○	IR or notification mode
16	Reserved 3	AN	2	67	●	○	VAVS reserved
17	System-cancel flag	A	1	69	●	○	`A` for a system cancellation

● set in the request message, ○ carried in the response message, ⊙ changed or populated in the response

Code Values

Direction Code

Value	Direction
`0`	Hecto Financial → Client institution
`1`	Hecto Financial → Bank
`2`	Bank → Hecto Financial
`3`	Client institution → Hecto Financial
`T`	Timeout
`9`	Transaction initiated from the web console

Set 3 whenever the client institution sends a request or response to Hecto Financial.

Origin Code

Value	Source
`A`	Hecto Financial operations terminal
`B`	Bank
`O`	Client institution
`W`	Hecto Financial web console

Delivery Mode

Value	Mode
`Y`	IR recipient-inquiry mode
`N`	SAF transaction-notification mode

The following banks support a choice between IR and notification mode.

Code	Bank
`020`	Woori Bank
`031`	iM Bank
`032`	BNK Busan Bank
`039`	BNK Kyongnam Bank

Unique Key

Use the following combination to identify a deposit, recipient inquiry, or cancellation:

Transaction date (8) + Institution code (8) + Transaction number (7)

For client-initiated remittance, holder-name inquiry, and reconciliation, generate a user transaction number that is unique for the day.

Building a Response

Convert the transaction type to the response code, for example 1000 → 1100.
Change the direction code to 3.
Set the processing result in the response-code field.
Populate the body account-holder name when required for inquiry or deposit responses.
Do not repurpose reserved fields.

System Cancellation

A system-cancellation message carries A in the common-header cancellation flag.

Banks that may initiate a system cancellation (as of July 24, 2026):

Code	Bank	Code	Bank
`003`	Industrial Bank of Korea (IBK)	`037`	Jeonbuk Bank
`020`	Woori Bank	`039`	BNK Kyongnam Bank
`023`	Standard Chartered Bank Korea	`071`	Korea Post
`027`	Citibank Korea	`088`	Shinhan Bank
`031`	iM Bank	`092`	Toss Bank
`032`	BNK Busan Bank
`035`	Jeju Bank

Always Apply a System Cancellation

A system cancellation has already been completed by the bank. Reverse the original deposit in your ledger regardless of whether your response is delivered successfully.

Need technical support?

Code Samples

HectoFinancial GitHub