TradedFlatSwitch (FIX tag 258)

BooleanFIX 4.4FIX 5.0 SP2

TradedFlatSwitch (tag 258) is a Boolean field defined in FIX 4.4 and FIX 5.0 SP2. It appears in 1 message type, always optionally. It is an enumerated field with 2 defined values.

At a glance

Tag: 258
Name: TradedFlatSwitch
Datatype: Boolean (char)
Dialects: FIX 4.4 and FIX 5.0 SP2
Messages: 1
Valid values: 2

What the specification says

FIX 4.4

Driver and part of trade in the event that the Security Master file was wrong at the point of entry (Note tag # was reserved in FIX 4.1, added in FIX 4.3)

FIX 5.0 SP2

Driver and part of trade in the event that the Security Master file was wrong at the point of entry(Note tag # was reserved in FIX 4.1, added in FIX 4.3)

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

A real message using tag 258

ExecutionReport · FIX 4.4

Tag	Field	Wire value	Meaning
8	BeginString	FIX.4.4
9	BodyLength	139
35	MsgType	8	Execution Report
49	SenderCompID	BOARTEAM
56	TargetCompID	COUNTERPARTY
34	MsgSeqNum	2
52	SendingTime	20240101-12:00:00.000
37	OrderID	ORD-10042
17	ExecID	EXEC-88117
150	ExecType	0	New
39	OrdStatus	0	New
54	Side	1	Buy
151	LeavesQty	0
14	CumQty	1000000
6	AvgPx	1.09215
258	TradedFlatSwitch	N	Not Traded Flat
10	CheckSum	074

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.

Valid values

A value outside this list is not a parse error — the message still decodes — but validate() reports it as validate/value-not-in-enum.

Value	Meaning	Symbolic name
Y	Traded Flat	YES / TRADED_FLAT
N	Not Traded Flat	NO / NOT_TRADED_FLAT

Where tag 258 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 5.0 SP2	Where in the message
ExecutionReport	8	Optional	Optional	directly on the message body

Wire format

Y or N. Not 1/0, and not true/false. @boarteam/fix keeps the value as a string and, for enumerated fields, reports validate/value-not-in-enum when it is not a defined value.

Read tag 258 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 tradedFlatSwitch = message.fields[258]?.raw;// e.g. "Y" — Traded Flat// The dictionary also carries the labels:const label = fix.dictionary  .fieldByTag(258)  ?.enumValues?.find((e) => e.value === tradedFlatSwitch)  ?.description;

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