NoBidDescriptors (FIX tag 398)

NumInGroupFIX 4.4FIX 4.2group counter

NoBidDescriptors (tag 398) is a NumInGroup field defined in FIX 4.4 and FIX 4.2. It appears in 1 message type, always optionally. Its datatype is NumInGroup, which makes it a repeating-group counter: its value is the number of entries that follow, not a quantity in its own right.

At a glance

Tag: 398
Name: NoBidDescriptors
Datatype: NumInGroup (int)
Dialects: FIX 4.4 and FIX 4.2
Messages: 1

What the specification says

FIX 4.4

Number of BidDescriptor (400) entries.

FIX 4.2

Number of BidDescriptor entries.

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

A real message using tag 398

BidRequest · FIX 4.4

Tag	Field	Wire value	Meaning
8	BeginString	FIX.4.4
9	BodyLength	123
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
399	BidDescriptorType	1	Sector
418	BidTradeType	R	Risk Trade
419	BasisPxType	2	Closing Price at morning session
10	CheckSum	187

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 398 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

The number of entries in the repeating group that follows. The next field on the wire is the group's delimiter tag. @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 398 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);// NoBidDescriptors is a group counter, so the entries live on message.groups —// NOT on message.fields. message.fields[398] is undefined.const entries = message.groups[398] ?? [];for (const entry of entries) {  // entry.fields is keyed by tag; entry.groups holds nested groups}

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