BidDescriptor (FIX tag 400)

StringFIX 4.4FIX 4.2

BidDescriptor (tag 400) is a String field defined in FIX 4.4 and FIX 4.2. It appears in 1 message type, always optionally.

At a glance

Tag: 400
Name: BidDescriptor
Datatype: String
Dialects: FIX 4.4 and FIX 4.2
Messages: 1

What the specification says

FIX 4.4

BidDescriptor value. Usage depends upon BidDescriptorTyp (399). If BidDescriptorType = 1 Industrials etc. - Free text If BidDescriptorType =2 "FR" etc. - ISO Country Codes If BidDescriptorType =3 FT00, FT250, STOX - Free text

FIX 4.2

BidDescriptor value. Usage depends upon BidDescriptorType.

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

A real message using tag 400

BidRequest · FIX 4.4

Tag	Field	Wire value	Meaning
8	BeginString	FIX.4.4
9	BodyLength	147
35	MsgType	k	Bid Request
49	SenderCompID	BOARTEAM
56	TargetCompID	COUNTERPARTY
34	MsgSeqNum	2
52	SendingTime	20240101-12:00:00.000
391	ClientBidID	EXAMPLE
374	BidRequestTransType	N	New
393	TotNoRelatedSym	1
394	BidType	1	"Non Disclosed" Style (e.g. US/European)
398	NoBidDescriptors2 entries	2	repeating group
399	BidDescriptorType	1	Sector
400	BidDescriptor	EXAMPLE
399	BidDescriptorType	1	Sector
400	BidDescriptor	EXAMPLE
418	BidTradeType	R	Risk Trade
419	BasisPxType	2	Closing Price at morning session
10	CheckSum	125

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 400 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
BidRequest	k	Optional	Optional	inside the BidDescReqGrp component

Wire format

Free-form text. Any byte except the SOH separator is legal, so values are not trimmed or case-folded on the wire. @boarteam/fix keeps the value as a string; format rules are checked by validate(), which reports validate/invalid-value rather than throwing.

Read tag 400 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[400];field?.name;   // "BidDescriptor"field?.raw;    // the verbatim wire stringfield?.value;  // coerced to a string

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