AllocAcctIDSource (FIX tag 661)

intFIX 4.4FIX 5.0 SP2

AllocAcctIDSource (tag 661) is an int field defined in FIX 4.4 and FIX 5.0 SP2. It appears in 16 message types, always optionally.

At a glance

Tag: 661
Name: AllocAcctIDSource
Datatype: int
Dialects: FIX 4.4 and FIX 5.0 SP2
Messages: 16

What the specification says

FIX 4.4

Used to identify the source of the AllocAccount (79) code. See AcctIDSource (660) for valid values.

FIX 5.0 SP2

Used to identify the source of the AllocAccount (79) code.

Descriptions are quoted from the FIX Orchestra sources under the Apache 2.0 licence.

A real message using tag 661

NewOrderSingle · FIX 4.4

Tag	Field	Wire value	Meaning
8	BeginString	FIX.4.4
9	BodyLength	150
35	MsgType	D	Order – Single
49	SenderCompID	BOARTEAM
56	TargetCompID	COUNTERPARTY
34	MsgSeqNum	2
52	SendingTime	20240101-12:00:00.000
11	ClOrdID	ORD-10042
78	NoAllocs2 entries	2	repeating group
79	AllocAccount	EXAMPLE
661	AllocAcctIDSource	1
79	AllocAccount	EXAMPLE
661	AllocAcctIDSource	1
54	Side	1	Buy
60	TransactTime	20240101-12:00:00.000
40	OrdType	1	Market
10	CheckSum	094

Edit and decode it yourself

Shown with | separators for readability. On the wire FIX uses SOH (0x01), an invisible control byte — and because BodyLength and CheckSum are computed over the actual bytes, the two forms have different checksums. Both are valid and both decode here.

Open in the full decoder →

Generated from the FIX 4.4 dictionary and verified at build time: it parses and validates with no issues. Open the decoder to try your own message.

Where tag 661 appears

Requiredness is a property of the message, not of the field: the same tag can be optional in one message and conditionally required in another.

Message	MsgType	FIX 4.4	FIX 5.0 SP2	Where in the message
AllocationInstruction	J	Conditional	Optional	inside the AllocGrp component
AllocationInstructionAck	P	Conditional	Optional	inside the AllocAckGrp component
AllocationInstructionAlert	BM	—	Optional	inside the AllocGrp component
AllocationReport	AS	Conditional	Optional	inside the AllocGrp component
AllocationReportAck	AT	Conditional	Optional	inside the AllocAckGrp component
Confirmation	AK	Optional	Optional	directly on the message body
ConfirmationRequest	BH	Optional	Optional	directly on the message body
CrossOrderCancelReplaceRequest	t	Conditional	Optional	inside SideCrossOrdModGrp › PreAllocGrp
ExecutionReport	8	—	Optional	inside the PreAllocGrp component
MultilegOrderCancelReplace	AC	Conditional	Optional	inside the PreAllocMlegGrp component
NewOrderCross	s	Conditional	Optional	inside SideCrossOrdModGrp › PreAllocGrp
NewOrderList	E	Conditional	Optional	inside ListOrdGrp › PreAllocGrp
NewOrderMultileg	AB	Conditional	Optional	inside the PreAllocMlegGrp component
NewOrderSingle	D	Conditional	Optional	inside the PreAllocGrp component
OrderCancelReplaceRequest	G	Conditional	Optional	inside the PreAllocGrp component
SettlementInstructionRequest	AV	Conditional	Optional	directly on the message body
TradeCaptureReport	AE	Conditional	Optional	inside TrdCapRptSideGrp › TrdAllocGrp
TradeCaptureReportAck	AR	Conditional	Optional	inside the TrdAllocGrp component

Wire format

A whole number, optionally signed. Leading zeros are legal on the wire and are preserved in the raw value. @boarteam/fix parses the value as a number and reports parse/invalid-int when it does not lex as one; the raw string is kept either way.

Read tag 661 in TypeScript

decode.tsts

import { createFixEngine } from "@boarteam/fix";import { dictionary } from "@boarteam/fix-dict-fix44";const fix = createFixEngine(dictionary);const { message, issues } = fix.parse(raw);const field = message.fields[661];field?.name;   // "AllocAcctIDSource"field?.raw;    // the verbatim wire stringfield?.value;  // coerced to a number

Decode this in your own code

The same engine that produced the decoded example above is an Apache-2.0 npm package with zero runtime dependencies. It runs in Node and in the browser, and parse() returns problems as data instead of throwing.

npm i @boarteam/fix @boarteam/fix-dict-fix44

Try the decoder Source on GitHub