ApplSeqNum (FIX tag 1181)

SeqNumFIX 5.0 SP2

ApplSeqNum (tag 1181) is a SeqNum field defined in FIX 5.0 SP2. It appears in 23 message types, always optionally.

At a glance

Tag: 1181
Name: ApplSeqNum
Datatype: SeqNum (int)
Dialects: FIX 5.0 SP2
Messages: 23

What the specification says

Data sequence number to be used when FIX session is not in effect

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

A real message using tag 1181

ExecutionReport · FIX 5.0 SP2

Tag	Field	Wire value	Meaning
8	BeginString	FIXT.1.1
9	BodyLength	130
35	MsgType	8	ExecutionReport
49	SenderCompID	BOARTEAM
56	TargetCompID	COUNTERPARTY
34	MsgSeqNum	2
52	SendingTime	20240101-12:00:00.000
1181	ApplSeqNum	1
37	OrderID	ORD-10042
17	ExecID	EXEC-88117
150	ExecType	0	New
39	OrdStatus	0	New
54	Side	1	Buy
151	LeavesQty	0
14	CumQty	1000000
10	CheckSum	202

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 5.0 SP2 dictionary and verified at build time: it parses and validates with no issues. Open the decoder to try your own message.

Where tag 1181 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	Requiredness	Where in the message
AssignmentReport	AW	Optional	inside the ApplicationSequenceControl component
ContraryIntentionReport	BO	Optional	inside the ApplicationSequenceControl component
DerivativeSecurityList	AA	Optional	inside the ApplicationSequenceControl component
DerivativeSecurityListUpdateReport	BR	Optional	inside the ApplicationSequenceControl component
ExecutionReport	8	Optional	inside the ApplicationSequenceControl component
IOI	6	Optional	inside the ApplicationSequenceControl component
MarketDataIncrementalRefresh	X	Optional	inside the ApplicationSequenceControl component
MarketDataSnapshotFullRefresh	W	Optional	inside the ApplicationSequenceControl component
MarketDefinition	BU	Optional	inside the ApplicationSequenceControl component
MarketDefinitionUpdateReport	BV	Optional	inside the ApplicationSequenceControl component
News	B	Optional	inside the ApplicationSequenceControl component
PositionReport	AP	Optional	inside the ApplicationSequenceControl component
SecurityDefinition	d	Optional	inside the ApplicationSequenceControl component
SecurityDefinitionUpdateReport	BP	Optional	inside the ApplicationSequenceControl component
SecurityList	y	Optional	inside the ApplicationSequenceControl component
SecurityListUpdateReport	BK	Optional	inside the ApplicationSequenceControl component
SecurityStatus	f	Optional	inside the ApplicationSequenceControl component
SecurityTypes	w	Optional	inside the ApplicationSequenceControl component
SettlementObligationReport	BQ	Optional	inside the ApplicationSequenceControl component
TradeCaptureReport	AE	Optional	inside the ApplicationSequenceControl component
TradingSessionList	BJ	Optional	inside the ApplicationSequenceControl component
TradingSessionListUpdateReport	BS	Optional	inside the ApplicationSequenceControl component
TradingSessionStatus	h	Optional	inside the ApplicationSequenceControl component

Wire format

A positive sequence number. Session-level, and monotonic within a session. @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 1181 in TypeScript

decode.tsts

import { createFixEngine } from "@boarteam/fix";import { dictionary } from "@boarteam/fix-dict-fix50sp2";const fix = createFixEngine(dictionary);const { message, issues } = fix.parse(raw);const field = message.fields[1181];field?.name;   // "ApplSeqNum"field?.raw;    // the verbatim wire stringfield?.value;  // coerced to a number

Other SeqNum 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-fix50sp2

Try the decoder Source on GitHub