PositionEffect (FIX tag 77)

charFIX 4.4FIX 4.2

PositionEffect (tag 77) is a char field defined in FIX 4.4 and FIX 4.2. It appears in 12 message types, always optionally. It is an enumerated field with 4 defined values. FIX 4.2 calls this field OpenClose; the tag number is unchanged, so the two are the same field on the wire.

Also known as OpenClose

FIX 4.2 calls tag 77 OpenClose. It is the same field on the wire — only the name changed — so a message encoded by either side interoperates.

At a glance

Tag: 77
Name: PositionEffect
Datatype: char
Dialects: FIX 4.4 and FIX 4.2
Messages: 12
Valid values: 4

What the specification says

Indicates whether the resulting position after a trade should be an opening position or closing position. Used for omnibus accounting - where accounts are held on a gross basis instead of being netted together.

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

A real message using tag 77

NewOrderSingle · FIX 4.4

Tag	Field	Wire value	Meaning
8	BeginString	FIX.4.4
9	BodyLength	116
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
54	Side	1	Buy
60	TransactTime	20240101-12:00:00.000
40	OrdType	1	Market
77	PositionEffect	O	Open
10	CheckSum	240

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.

Valid values

A value outside this list is not a parse error — the message still decodes — but validate() reports it as validate/value-not-in-enum.

Value	Meaning	Symbolic name	Dialects
O	Open	OPEN / Open	FIX 4.4, FIX 4.2
C	Close	CLOSE / Close	FIX 4.4, FIX 4.2
R	Rolled	ROLLED	FIX 4.4
F	FIFO	FIFO	FIX 4.4

Where tag 77 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
AllocationInstruction	J	Optional	Optional	directly on the message body
AllocationReport	AS	Optional	—	directly on the message body
CrossOrderCancelReplaceRequest	t	Optional	—	inside the SideCrossOrdModGrp component
ExecutionReport	8	Optional	Optional	directly on the message body
MultilegOrderCancelReplace	AC	Optional	—	directly on the message body
NewOrderCross	s	Optional	—	inside the SideCrossOrdModGrp component
NewOrderList	E	Optional	Optional	inside the ListOrdGrp component
NewOrderMultileg	AB	Optional	—	directly on the message body
NewOrderSingle	D	Optional	Optional	directly on the message body
OrderCancelReplaceRequest	G	Optional	Optional	directly on the message body
TradeCaptureReport	AE	Optional	—	inside the TrdCapRptSideGrp component
TradeCaptureReportAck	AR	Optional	—	directly on the message body

Wire format

A single character. Most char fields are enumerated, so the value is one of a fixed set rather than arbitrary text. @boarteam/fix keeps the value as a string and, for enumerated fields, reports validate/value-not-in-enum when it is not a defined value.

Read tag 77 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 positionEffect = message.fields[77]?.raw;// e.g. "O" — Open// The dictionary also carries the labels:const label = fix.dictionary  .fieldByTag(77)  ?.enumValues?.find((e) => e.value === positionEffect)  ?.description;

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