RndPx (FIX tag 991)

PriceFIX 5.0 SP2

RndPx (tag 991) is a Price field defined in FIX 5.0 SP2. It appears in 5 message types, always optionally.

At a glance

Tag: 991
Name: RndPx
Datatype: Price (float)
Dialects: FIX 5.0 SP2
Messages: 5

What the specification says

Specifies average price rounded to quoted precision.

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

A real message using tag 991

TradeCaptureReport · FIX 5.0 SP2

Tag	Field	Wire value	Meaning
8	BeginString	FIXT.1.1
9	BodyLength	109
35	MsgType	AE	TradeCaptureReport
49	SenderCompID	BOARTEAM
56	TargetCompID	COUNTERPARTY
34	MsgSeqNum	2
52	SendingTime	20240101-12:00:00.000
32	LastQty	1000000
31	LastPx	1.09210
552	NoSides1 entry	1	repeating group
54	Side	1	Buy
991	RndPx	1.09210
10	CheckSum	147

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 991 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
AllocationInstruction	J	Optional	directly on the message body
AllocationInstructionAlert	BM	Optional	directly on the message body
AllocationReport	AS	Optional	directly on the message body
TradeCaptureReport	AE	Optional	directly on the message body
TradeCaptureReportAck	AR	Optional	directly on the message body

Wire format

A decimal price. Precision is a venue convention, not a protocol rule, so compare the raw string when exactness matters. @boarteam/fix parses the value as a number and reports parse/invalid-float when it does not lex as one; the raw string is kept so precision and trailing zeros are never lost.

Read tag 991 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[991];field?.name;   // "RndPx"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-fix50sp2

Try the decoder Source on GitHub