MDReqID (FIX tag 262)

StringFIX 4.4FIX 4.2

MDReqID (tag 262) is a String field defined in FIX 4.4 and FIX 4.2. It appears in 4 message types and is required in 2 of them.

At a glance

Tag: 262
Name: MDReqID
Datatype: String
Dialects: FIX 4.4 and FIX 4.2
Messages: 4

What the specification says

Unique identifier for Market Data Request

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

A real message using tag 262

MarketDataSnapshotFullRefresh · FIX 4.4

Tag	Field	Wire value	Meaning
8	BeginString	FIX.4.4
9	BodyLength	85
35	MsgType	W	Market Data-Snapshot/Full Refresh
49	SenderCompID	BOARTEAM
56	TargetCompID	COUNTERPARTY
34	MsgSeqNum	2
52	SendingTime	20240101-12:00:00.000
262	MDReqID	REQ-1
268	NoMDEntries1 entry	1	repeating group
269	MDEntryType	0	Bid
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 262 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
MarketDataIncrementalRefresh	X	Optional	Optional	directly on the message body
MarketDataRequest	V	Required	Required	directly on the message body
MarketDataRequestReject	Y	Required	Required	directly on the message body
MarketDataSnapshotFullRefresh	W	Optional	Optional	directly on the message body

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 262 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[262];field?.name;   // "MDReqID"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