MaxShow (FIX tag 210)

QtyFIX 4.4FIX 4.2

MaxShow (tag 210) is a Qty field defined in FIX 4.4 and FIX 4.2. It appears in 8 message types, always optionally.

At a glance

Tag: 210
Name: MaxShow
Datatype: Qty (float)
Dialects: FIX 4.4 and FIX 4.2
Messages: 8

What the specification says

FIX 4.4

Maximum quantity (e.g. number of shares) within an order to be shown to other customers (i.e. sent via an IOI). (Prior to FIX 4.2 this field was of type int)

FIX 4.2

Maximum number of shares within an order to be shown to other customers (i.e. sent via an IOI). (Prior to FIX 4.2 this field was of type int)

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

A real message using tag 210

NewOrderSingle · FIX 4.4

Tag	Field	Wire value	Meaning
8	BeginString	FIX.4.4
9	BodyLength	123
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
210	MaxShow	1000000
10	CheckSum	021

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 210 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
CrossOrderCancelReplaceRequest	t	Optional	—	directly on the message body
ExecutionReport	8	Optional	Optional	directly on the message body
MultilegOrderCancelReplace	AC	Optional	—	directly on the message body
NewOrderCross	s	Optional	—	directly on the message body
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

Wire format

A decimal quantity. Fractional quantities are legal, which is why this is a float family rather than an integer. @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 210 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[210];field?.name;   // "MaxShow"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-fix44

Try the decoder Source on GitHub