EncodedUnderlyingSecurityDesc (FIX tag 365)
dataFIX 4.4FIX 4.2
EncodedUnderlyingSecurityDesc (tag 365) is a data field defined in FIX 4.4 and FIX 4.2. It appears in 59 message types, always optionally. It is length-prefixed — tag 364 carries the byte count, so the value may contain the SOH separator without breaking the message.
At a glance
What the specification says
FIX 4.4
Encoded (non-ASCII characters) representation of the UnderlyingSecurityDesc (307) field in the encoded format specified via the MessageEncoding (347) field. If used, the ASCII (English) representation should also be specified in the UnderlyingSecurityDesc field.
FIX 4.2
Encoded (non-ASCII characters) representation of the UnderlyingSecurityDesc field in the encoded format specified via the MessageEncoding field. If used, the ASCII (English) representation should also be specified in the UnderlyingSecurityeDesc field.
Descriptions are quoted from the FIX Orchestra sources under the Apache 2.0 licence.
A real message using tag 365
NewOrderSingle · FIX 4.4
| Tag | Field | Wire value | Meaning |
|---|---|---|---|
| 8 | BeginString | FIX.4.4 | |
| 9 | BodyLength | 177 | |
| 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 | |
| 711 | NoUnderlyings2 entries | 2 | repeating group |
| 311 | UnderlyingSymbol | EXAMPLE | |
| 364 | EncodedUnderlyingSecurityDescLen | 7 | |
| 365 | EncodedUnderlyingSecurityDesc | EXAMPLE | |
| 311 | UnderlyingSymbol | EXAMPLE | |
| 364 | EncodedUnderlyingSecurityDescLen | 7 | |
| 365 | EncodedUnderlyingSecurityDesc | EXAMPLE | |
| 54 | Side | 1 | Buy |
| 60 | TransactTime | 20240101-12:00:00.000 | |
| 40 | OrdType | 1 | Market |
| 10 | CheckSum | 183 |
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.
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 365 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 |
|---|---|---|---|---|
| Advertisement | 7 | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| AllocationInstruction | J | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| AllocationReport | AS | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| AssignmentReport | AW | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| CollateralAssignment | AY | Conditional | — | inside UndInstrmtCollGrp › UnderlyingInstrument |
| CollateralInquiry | BB | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| CollateralInquiryAck | BG | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| CollateralReport | BA | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| CollateralRequest | AX | Conditional | — | inside UndInstrmtCollGrp › UnderlyingInstrument |
| CollateralResponse | AZ | Conditional | — | inside UndInstrmtCollGrp › UnderlyingInstrument |
| Confirmation | AK | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| CrossOrderCancelReplaceRequest | t | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| CrossOrderCancelRequest | u | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| DerivativeSecurityList | AA | Conditional | — | inside the UnderlyingInstrument component |
| DerivativeSecurityListRequest | z | Conditional | — | inside the UnderlyingInstrument component |
| DontKnowTrade | Q | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| C | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument | |
| ExecutionReport | 8 | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| IOI | 6 | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| ListStrikePrice | m | Conditional | — | inside UndInstrmtStrkPxGrp › UnderlyingInstrument |
| MarketDataIncrementalRefresh | X | Conditional | — | inside MDIncGrp › UndInstrmtGrp › UnderlyingInstrument |
| MarketDataRequest | V | Conditional | — | inside InstrmtMDReqGrp › UndInstrmtGrp › UnderlyingInstrument |
| MarketDataSnapshotFullRefresh | W | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| MassQuote | i | Conditional | Optional | inside QuotSetGrp › UnderlyingInstrument |
| MassQuoteAcknowledgement | b | Conditional | Optional | inside QuotSetAckGrp › UnderlyingInstrument |
| MultilegOrderCancelReplace | AC | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| NewOrderCross | s | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| NewOrderList | E | Conditional | — | inside ListOrdGrp › UndInstrmtGrp › UnderlyingInstrument |
| NewOrderMultileg | AB | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| NewOrderSingle | D | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| News | B | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| OrderCancelReplaceRequest | G | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| OrderCancelRequest | F | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| OrderMassCancelReport | r | Conditional | — | inside the UnderlyingInstrument component |
| OrderMassCancelRequest | q | Conditional | — | inside the UnderlyingInstrument component |
| OrderMassStatusRequest | AF | Conditional | — | inside the UnderlyingInstrument component |
| OrderStatusRequest | H | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| PositionMaintenanceReport | AM | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| PositionMaintenanceRequest | AL | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| PositionReport | AP | Conditional | — | inside PosUndInstrmtGrp › UnderlyingInstrument |
| Quote | S | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| QuoteCancel | Z | Conditional | — | inside QuotCxlEntriesGrp › UndInstrmtGrp › UnderlyingInstrument |
| QuoteRequest | R | Conditional | — | inside QuotReqGrp › UndInstrmtGrp › UnderlyingInstrument |
| QuoteRequestReject | AG | Conditional | — | inside QuotReqRjctGrp › UndInstrmtGrp › UnderlyingInstrument |
| QuoteResponse | AJ | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| QuoteStatusReport | AI | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| QuoteStatusRequest | a | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| RFQRequest | AH | Conditional | — | inside RFQReqGrp › UndInstrmtGrp › UnderlyingInstrument |
| RequestForPositions | AN | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| RequestForPositionsAck | AO | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| SecurityDefinition | d | Conditional | Optional | inside UndInstrmtGrp › UnderlyingInstrument |
| SecurityDefinitionRequest | c | Conditional | Optional | inside UndInstrmtGrp › UnderlyingInstrument |
| SecurityList | y | Conditional | — | inside SecListGrp › UndInstrmtGrp › UnderlyingInstrument |
| SecurityListRequest | x | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| SecurityStatus | f | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| SecurityStatusRequest | e | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| TradeCaptureReport | AE | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| TradeCaptureReportRequest | AD | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
| TradeCaptureReportRequestAck | AQ | Conditional | — | inside UndInstrmtGrp › UnderlyingInstrument |
Wire format
Raw bytes, length-prefixed by a partner field. The value may legally contain the SOH separator, which is why the length matters. @boarteam/fix reads the partner length field first and takes exactly that many bytes, so an embedded separator does not truncate the value.
Read tag 365 in TypeScript
import { createFixEngine } from "@boarteam/fix";import { dictionary } from "@boarteam/fix-dict-fix44";const fix = createFixEngine(dictionary);const { message, issues } = fix.parse(raw);// Length-prefixed: tag 364 carries the byte count, so the// value may contain the SOH separator without breaking the message.const length = message.fields[364]?.value;const encodedUnderlyingSecurityDesc = message.fields[365]?.raw;Other data fields
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