AggregatedBook (FIX tag 266)
AggregatedBook (tag 266) is a Boolean field defined in FIX 4.4 and FIX 4.2. It appears in 1 message type, always optionally. It is an enumerated field with 2 defined values.
At a glance
- Tag
- 266
- Name
- AggregatedBook
- Datatype
- Boolean (char)
- Dialects
- FIX 4.4 and FIX 4.2
- Messages
- 1
- Valid values
- 2
What the specification says
Specifies whether or not book entries should be aggregated.
Descriptions are quoted from the FIX Orchestra sources under the Apache 2.0 licence.
A real message using tag 266
| Tag | Field | Wire value | Meaning |
|---|---|---|---|
| 8 | BeginString | FIX.4.4 | |
| 9 | BodyLength | 120 | |
| 35 | MsgType | V | Market Data Request |
| 49 | SenderCompID | BOARTEAM | |
| 56 | TargetCompID | COUNTERPARTY | |
| 34 | MsgSeqNum | 2 | |
| 52 | SendingTime | 20240101-12:00:00.000 | |
| 262 | MDReqID | REQ-1 | |
| 263 | SubscriptionRequestType | 0 | Snapshot |
| 264 | MarketDepth | 1 | |
| 266 | AggregatedBook | N | Multiple entries per side per price allowed |
| 267 | NoMDEntryTypes1 entry | 1 | repeating group |
| 269 | MDEntryType | 0 | Bid |
| 146 | NoRelatedSym1 entry | 1 | repeating group |
| 55 | Symbol | EUR/USD | |
| 10 | CheckSum | 048 |
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.
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 | one book entry per side per price | YES / BookEntriesToBeAggregated |
| N | Multiple entries per side per price allowed | NO / BookEntriesShouldNotBeAggregated |
Where tag 266 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 |
|---|---|---|---|---|
| MarketDataRequest | V | 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 266 in TypeScript
import { createFixEngine } from "@boarteam/fix";import { dictionary } from "@boarteam/fix-dict-fix44";const fix = createFixEngine(dictionary);const { message, issues } = fix.parse(raw);const aggregatedBook = message.fields[266]?.raw;// e.g. "Y" — one book entry per side per price// The dictionary also carries the labels:const label = fix.dictionary .fieldByTag(266) ?.enumValues?.find((e) => e.value === aggregatedBook) ?.description;Other Boolean fields
- 258TradedFlatSwitch
- 208NotifyBrokerOfCredit
- 325UnsolicitedIndicator
- 328InViewOfCommon
- 329DueToRelated
- 377SolicitedFlag
- 141ResetSeqNumFlag
- 130IOINaturalFlag
- 123GapFillFlag
- 121ForexReq
- 411ExchangeForPhysical
- 114LocateReqd
- 113ReportToExch
- 97PossResend
- 464TestMessageIndicator
- 43PossDupFlag
- 547MDImplicitDelete
- 570PreviouslyReported
- 575OddLot
- 636WorkingIndicator
- 650LegalConfirm
- 700ReversalIndicator
- 719ContraryInstructionIndicator
- 720PriorSpreadIndicator
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