MaturityMonthYearFormat (FIX tag 1303)

intFIX 5.0 SP2

MaturityMonthYearFormat (tag 1303) is an int field defined in FIX 5.0 SP2. It appears in 6 message types, always optionally. It is an enumerated field with 3 defined values.

At a glance

Tag: 1303
Name: MaturityMonthYearFormat
Datatype: int
Dialects: FIX 5.0 SP2
Messages: 6
Valid values: 3

What the specification says

Format used to generate the MaturityMonthYear for each option

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

A real message using tag 1303

SecurityDefinition · FIX 5.0 SP2

Tag	Field	Wire value	Meaning
8	BeginString	FIXT.1.1
9	BodyLength	147
35	MsgType	d	SecurityDefinition
49	SenderCompID	BOARTEAM
56	TargetCompID	COUNTERPARTY
34	MsgSeqNum	2
52	SendingTime	20240101-12:00:00.000
1310	NoMarketSegments1 entry	1	repeating group
1301	MarketID	XNAS
1201	NoStrikeRules1 entry	1	repeating group
1223	StrikeRuleID	EXAMPLE
1236	NoMaturityRules2 entries	2	repeating group
1222	MaturityRuleID	EXAMPLE
1303	MaturityMonthYearFormat	0	YearMonth Only (default)
1222	MaturityRuleID	EXAMPLE
1303	MaturityMonthYearFormat	0	YearMonth Only (default)
10	CheckSum	225

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 5.0 SP2 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
0	YearMonth Only (default)	YEARMONTH_ONLY
1	YearMonthDay	YEARMONTHDAY
2	YearMonthWeek	YEARMONTHWEEK

Where tag 1303 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	Requiredness	Where in the message
DerivativeSecurityList	AA	Optional	inside DerivativeSecurityDefinition › MarketSegmentGrp › StrikeRules › MaturityRules
DerivativeSecurityListUpdateReport	BR	Optional	inside DerivativeSecurityDefinition › MarketSegmentGrp › StrikeRules › MaturityRules
SecurityDefinition	d	Optional	inside MarketSegmentGrp › StrikeRules › MaturityRules
SecurityDefinitionUpdateReport	BP	Optional	inside MarketSegmentGrp › StrikeRules › MaturityRules
SecurityList	y	Optional	inside SecListGrp › StrikeRules › MaturityRules
SecurityListUpdateReport	BK	Optional	inside SecLstUpdRelSymGrp › StrikeRules › MaturityRules

Wire format

A whole number, optionally signed. Leading zeros are legal on the wire and are preserved in the raw value. @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 1303 in TypeScript

decode.tsts

import { createFixEngine } from "@boarteam/fix";import { dictionary } from "@boarteam/fix-dict-fix50sp2";const fix = createFixEngine(dictionary);const { message, issues } = fix.parse(raw);const maturityMonthYearFormat = message.fields[1303]?.raw;// e.g. "0" — YearMonth Only (default)// The dictionary also carries the labels:const label = fix.dictionary  .fieldByTag(1303)  ?.enumValues?.find((e) => e.value === maturityMonthYearFormat)  ?.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-fix50sp2

Try the decoder Source on GitHub