EncodedUnderlyingIssuer (FIX tag 363)

dataFIX 4.4FIX 4.2

EncodedUnderlyingIssuer (tag 363) is a data field defined in FIX 4.4 and FIX 4.2. It appears in 59 message types, always optionally. It is length-prefixed — tag 362 carries the byte count, so the value may contain the SOH separator without breaking the message.

At a glance

Tag: 363
Name: EncodedUnderlyingIssuer
Datatype: data
Dialects: FIX 4.4 and FIX 4.2
Messages: 59
Length field: tag 362

What the specification says

FIX 4.4

Encoded (non-ASCII characters) representation of the UnderlyingIssuer (306) field in the encoded format specified via the MessageEncoding (347) field. If used, the ASCII (English) representation should also be specified in the UnderlyingIssuer field.

FIX 4.2

Encoded (non-ASCII characters) representation of the UnderlyingIssuer field in the encoded format specified via the MessageEncoding field. If used, the ASCII (English) representation should also be specified in the UnderlyingIssuer field.

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

A real message using tag 363

NewOrderSingle · FIX 4.4

Tag	Field	Wire value	Meaning
8	BeginString	FIX.4.4
9	BodyLength	177
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
711	NoUnderlyings2 entries	2	repeating group
311	UnderlyingSymbol	EXAMPLE
362	EncodedUnderlyingIssuerLen	7
363	EncodedUnderlyingIssuer	EXAMPLE
311	UnderlyingSymbol	EXAMPLE
362	EncodedUnderlyingIssuerLen	7
363	EncodedUnderlyingIssuer	EXAMPLE
54	Side	1	Buy
60	TransactTime	20240101-12:00:00.000
40	OrdType	1	Market
10	CheckSum	175

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 363 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 4.2	Where in the message
Advertisement	7	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
AllocationInstruction	J	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
AllocationReport	AS	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
AssignmentReport	AW	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
CollateralAssignment	AY	Conditional	—	inside UndInstrmtCollGrp › UnderlyingInstrument
CollateralInquiry	BB	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
CollateralInquiryAck	BG	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
CollateralReport	BA	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
CollateralRequest	AX	Conditional	—	inside UndInstrmtCollGrp › UnderlyingInstrument
CollateralResponse	AZ	Conditional	—	inside UndInstrmtCollGrp › UnderlyingInstrument
Confirmation	AK	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
CrossOrderCancelReplaceRequest	t	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
CrossOrderCancelRequest	u	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
DerivativeSecurityList	AA	Conditional	—	inside the UnderlyingInstrument component
DerivativeSecurityListRequest	z	Conditional	—	inside the UnderlyingInstrument component
DontKnowTrade	Q	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
Email	C	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
ExecutionReport	8	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
IOI	6	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
ListStrikePrice	m	Conditional	—	inside UndInstrmtStrkPxGrp › UnderlyingInstrument
MarketDataIncrementalRefresh	X	Conditional	—	inside MDIncGrp › UndInstrmtGrp › UnderlyingInstrument
MarketDataRequest	V	Conditional	—	inside InstrmtMDReqGrp › UndInstrmtGrp › UnderlyingInstrument
MarketDataSnapshotFullRefresh	W	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
MassQuote	i	Conditional	Optional	inside QuotSetGrp › UnderlyingInstrument
MassQuoteAcknowledgement	b	Conditional	Optional	inside QuotSetAckGrp › UnderlyingInstrument
MultilegOrderCancelReplace	AC	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
NewOrderCross	s	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
NewOrderList	E	Conditional	—	inside ListOrdGrp › UndInstrmtGrp › UnderlyingInstrument
NewOrderMultileg	AB	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
NewOrderSingle	D	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
News	B	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
OrderCancelReplaceRequest	G	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
OrderCancelRequest	F	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
OrderMassCancelReport	r	Conditional	—	inside the UnderlyingInstrument component
OrderMassCancelRequest	q	Conditional	—	inside the UnderlyingInstrument component
OrderMassStatusRequest	AF	Conditional	—	inside the UnderlyingInstrument component
OrderStatusRequest	H	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
PositionMaintenanceReport	AM	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
PositionMaintenanceRequest	AL	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
PositionReport	AP	Conditional	—	inside PosUndInstrmtGrp › UnderlyingInstrument
Quote	S	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
QuoteCancel	Z	Conditional	—	inside QuotCxlEntriesGrp › UndInstrmtGrp › UnderlyingInstrument
QuoteRequest	R	Conditional	—	inside QuotReqGrp › UndInstrmtGrp › UnderlyingInstrument
QuoteRequestReject	AG	Conditional	—	inside QuotReqRjctGrp › UndInstrmtGrp › UnderlyingInstrument
QuoteResponse	AJ	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
QuoteStatusReport	AI	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
QuoteStatusRequest	a	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
RFQRequest	AH	Conditional	—	inside RFQReqGrp › UndInstrmtGrp › UnderlyingInstrument
RequestForPositions	AN	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
RequestForPositionsAck	AO	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
SecurityDefinition	d	Conditional	Optional	inside UndInstrmtGrp › UnderlyingInstrument
SecurityDefinitionRequest	c	Conditional	Optional	inside UndInstrmtGrp › UnderlyingInstrument
SecurityList	y	Conditional	—	inside SecListGrp › UndInstrmtGrp › UnderlyingInstrument
SecurityListRequest	x	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
SecurityStatus	f	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
SecurityStatusRequest	e	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
TradeCaptureReport	AE	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
TradeCaptureReportRequest	AD	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument
TradeCaptureReportRequestAck	AQ	Conditional	—	inside UndInstrmtGrp › UnderlyingInstrument

Wire format

Raw bytes, length-prefixed by a partner field. The value may legally contain the SOH separator, which is why the length matters. @boarteam/fix reads the partner length field first and takes exactly that many bytes, so an embedded separator does not truncate the value.

Read tag 363 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);// Length-prefixed: tag 362 carries the byte count, so the// value may contain the SOH separator without breaking the message.const length = message.fields[362]?.value;const encodedUnderlyingIssuer = message.fields[363]?.raw;

Other data fields

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