TradSesPreCloseTime (FIX tag 343)

UTCTimestampFIX 4.4FIX 4.2FIX 5.0 SP2

TradSesPreCloseTime (tag 343) is an UTCTimestamp field defined in FIX 4.4, FIX 4.2 and FIX 5.0 SP2. It appears in 1 message type, always optionally.

At a glance

Tag: 343
Name: TradSesPreCloseTime
Datatype: UTCTimestamp (String)
Format: YYYYMMDD-HH:MM:SS[.sss]
Dialects: FIX 4.4, FIX 4.2 and FIX 5.0 SP2
Messages: 1

What the specification says

Time of the pre-closed of the trading session

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

A real message using tag 343

TradingSessionStatus · FIX 4.4

Tag	Field	Wire value	Meaning
8	BeginString	FIX.4.4
9	BodyLength	107
35	MsgType	h	Trading Session Status
49	SenderCompID	BOARTEAM
56	TargetCompID	COUNTERPARTY
34	MsgSeqNum	2
52	SendingTime	20240101-12:00:00.000
336	TradingSessionID	REGULAR
340	TradSesStatus	0	Unknown
343	TradSesPreCloseTime	20240101-12:00:00.000
10	CheckSum	234

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 343 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	FIX 5.0 SP2	Where in the message
TradingSessionList	BJ	—	—	Optional	inside the TrdSessLstGrp component
TradingSessionListUpdateReport	BS	—	—	Optional	inside the TrdSessLstGrp component
TradingSessionStatus	h	Optional	Optional	Optional	directly on the message body

Wire format

A UTC date and time. The fractional-seconds part is optional, so two timestamps can be equal but not byte-identical. @boarteam/fix keeps the value as a string; format rules are checked by validate(), which reports validate/invalid-value rather than throwing.

Read tag 343 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[343];field?.name;   // "TradSesPreCloseTime"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