# Cboe Titanium U.S. Options Auction Feed Specification

Version 1.1.41 · July 21, 2026

## Introduction

The Cboe Titanium U.S. Options Auction Feed specification may be used to deliver Auction message information for Cboe Options (C1) and EDGX Options Exchanges.

**Table 1. Multicast Options Auction Feed Descriptions**

| Exchange | Shaping | Served From Data Center (Primary/Secondary) | Multicast Feed ID |
|---|---|---|---|
| C1 Options | Gig | Primary | CAA |
| C1 Options | Gig | Primary | CBA |
| C1 Options | Gig | Secondary | CEA |
| EDGX Options | Gig | Primary | EAA |
| EDGX Options | Gig | Primary | EBA |
| EDGX Options | Gig | Secondary | EEA |

Cboe Members may also use Cboe Multicast PITCH to receive auction messages as well as real-time depth of book quotations and execution information. Refer to the Cboe Titanium U.S. Equities/Options Multicast Depth of Book (PITCH) Specification for more information.

### 24x5 Feed Hours and System Restart (C1 Only)

For C1 Options operating in 24x5 mode, the Auction feed starts on Sunday at approximately 1:00 p.m. ET and shuts down on Friday at approximately 5:30 p.m. ET. A daily restart occurs between 5:30 and 7:00 p.m. ET each day at which time sequences will be reset. The daily restart is typically observed between 5:30 p.m. and 6:00 p.m. ET, but could occur later if needed for operational reasons. Feed startup and shutdown times may be adjusted without notice. Persisted GTC, GTD, and DAY orders are added back into the order book starting at approximately 10 minutes prior to the scheduled queuing time for each underlying symbol.

### Feed Connectivity Requirements

Gig Shaped feeds are available to members with a minimum of 1 GB/s of connectivity to Cboe via cross connect or dedicated circuit.

Members with sufficient connectivity may choose to take both the Gig-Shaped feeds from one of Cboe datacenters and arbitrate the feeds to recover lost data. Alternatively, members may choose to arbitrate feeds from both datacenters. It should be noted that feeds from the secondary datacenter will have additional latency for those connected with Cboe in the primary data center due to proximity and business continuity processing.

Cboe Options Auction Feed real-time events are delivered using a published range of multicast addresses divided by symbol range units.

## Protocol

C1 and EDGX Options users may receive the Cboe Options Auction Feed protocol over multicast only. The Cboe Options Auction Feed cannot be used to enter orders.

### Message Format

Cboe Options Auction Feed protocol messages are delivered un-sequenced and may not be retrieved if missed.

Cboe Members familiar with the Multicast Depth of Book protocol should find it very easy to reuse that code to process the Cboe Options Auction Feed. All multicast delivered events will be self-contained. Developers can assume that delivered data will not cross frame boundaries and a single Ethernet frame will contain only one Unit Header with associated data.

The Cboe Options Auction Feed is comprised of a series of dynamic length un-sequenced messages. Each message begins with Length and Message Type fields. Cboe reserves the right to add message types and grow the length of any message without notice. Members should develop their decoders to handle unknown message types and messages beyond the expected length. Messages will only be grown to add additional data to the end of a message.

### Data Types

The following field types are used within the `Sequenced Unit Header` and PITCH 2.X.

- Alphanumeric fields are left justified ASCII fields and space padded on the right.
- Binary fields are unsigned and sized to `Length` bytes and ordered using Little Endian convention (least significant byte first).
- Binary Long Price fields are unsigned Little Endian encoded 8 byte binary fields with 4 implied decimal places ( `denominator`=10,000).
- Multiplier fields are unsigned Little Endian encoded 4 byte binary fields with 1 implied decimal place ( `denominator`=10).
- Bit Field fields are fixed width fields with each bit representing a Boolean flag (the 0 bit is the lowest significant bit; the 7 bit is the highest significant bit).
- Printable ASCII fields are left justified ASCII fields that are space padded on the right that may include ASCII values in the range of 0x20 - 0x7e.
- Binary Date fields are 4 byte unsigned Little Endian values where the base-10 representation is the YYYYMMDD representation of that date. For example, October 30, 2023 would be represented as 20,231,030 (20231030).
- Time Offset fields are 4 byte unsigned Little Endian values that represent the number of nanoseconds since the last `Time` message. These fields are populated to nanosecond precision. For example, a nano time of 1,737,580,407,123,456,789 ("Wednesday, January 22, 2025 9:13:27.123456789") would return value = 123456789.

### Sequenced Unit Header

The `Sequenced Unit Header` is used for all Cboe Options Auction Feed messages.

Unsequenced data may be delivered using the `Sequenced Unit Header`. Sequenced headers will have a 0 value for the sequence field and potentially for the unit field.

**Table 1. Sequenced Unit Header**

| Field | Offset | Length | Value/Type | Description |
|---|---|---|---|---|
| Hdr Length | 0 | 2 | Binary | Length of entire block of messages. Includes this header and Hdr Count messages to follow. |
| Hdr Count | 2 | 1 | Binary | Number of messages to follow this header. |
| Hdr Unit | 3 | 1 | Binary | Unit that applies to messages included in this header. |
| Hdr Sequence | 4 | 4 | Binary | Will be zero. |
| Total Length = 8 bytes |  |  |  |  |

### Heartbeat Messages

The `Sequenced Unit Header` with a count field set to `0` will be used for heartbeat messages. During trading hours heartbeat messages will be sent if no data has been delivered within 1 second.

Outside of trading hours Cboe sends heartbeat messages on all real-time channels to help users validate multicast connectivity. Heartbeat messages may not be sent from 12:00 a.m. - 1:00 a.m. ET or during maintenance windows.

## Cboe Options Auction Feed Messages

### Time Reference (C1 Only)

The `Time Reference` message is used to provide a midnight reference point for recipients of the feed. It is sent whenever the system starts up and when the system crosses a midnight boundary. All subsequent `Time` messages for the same unit will the use the last Midnight Reference until another `Time Reference` message is received for that unit. The `Time Reference` message includes the Trade Date, so most other sequenced messages will not include that information.

`Time Reference` messages will be included in a spin response.

**Table 1. Time Reference**

| Field Name | Offset | Length | Type/(Value) | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field. |
| Message Type | 1 | 1 | 0xB1 | `Time Reference` Message |
| Midnight Reference | 2 | 4 | Binary | Midnight Eastern Time reference time for subsequent `Time` messages, expressed as number of whole seconds since the Epoch (midnight January 1, 1970 UTC). |
| Time | 6 | 4 | Binary | Number of whole seconds elapsed since the start of the current Eastern Time calendar day, derived by converting the current Eastern wall clock time (HH:MM:SS) to seconds. On Daylight Saving Time transition days, Time reflects wall clock seconds and does not adjust for the UTC offset change. On a DST spring-forward day, the maximum value will be 82,799 (23 hours). On a DST fall-back day, values between 3,600 and 7,199 will appear twice. Recipients requiring unambiguous absolute timestamps should use Epoch Time (where available) or Midnight Reference in the `Time Reference` message. |
| Time Offset | 10 | 4 | Time Offset | Nanosecond offset from last unit timestamp. |
| Trade Date | 14 | 4 | Binary Date | Current Trade Date |
| Total Length = 18 bytes |  |  |  |  |

### Time

A `Time` message is immediately generated and sent when there is an Auction event for a given clock second. If there is no Auction event for a given clock second, then no `Time` message is sent for that second. All subsequent time offset fields for the same unit will use the new `Time` value as the base until another `Time` message is received for the same unit.

**Table 1. Time**

| Field Name | Offset | Length | Type/(Value) | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field |
| Message Type | 1 | 1 | 0x20 | `Time` Message |
| Time | 2 | 4 | Binary | Number of whole seconds elapsed since the start of the current Eastern Time calendar day, derived by converting the current Eastern wall clock time (HH:MM:SS) to seconds. On Daylight Saving Time transition days, Time reflects wall clock seconds and does not adjust for the UTC offset change. On a DST spring-forward day, the maximum value will be 82,799 (23 hours). On a DST fall-back day, values between 3,600 and 7,199 will appear twice. Recipients requiring unambiguous absolute timestamps should use Epoch Time (where available) or Midnight Reference in the `Time Reference` message. |
| Epoch Time | 6 | 4 | Binary | C1 Only Number of whole seconds since the Epoch (midnight January 1, 1970 UTC). |
| Total Length = 6 bytes, 10 bytes on C1 Only |  |  |  |  |

### Unit Clear

The `Unit Clear` message instructs feed recipients to clear all orders for the Cboe book in the unit specified in the `Sequenced Unit Header`. This message will be sent at startup each day. It would also be distributed in certain recovery events such as a data center fail-over.

**Table 1. Unit Clear**

| Field Name | Offset | Length | Type/(Value) | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field |
| Message Type | 1 | 1 | 0x97 | `Unit Clear` Message |
| Time Offset | 2 | 4 | Time Offset | Nanosecond offset from last unit timestamp |
| Total Length = 6 bytes |  |  |  |  |

### Auction Notification

`Auction Notification` messages are used to disseminate order details of an auction. Auctions will be available for a defined period of time known as the exposure period.

**Table 1. Auction Notification**

| Field Name | Offset | Length | Type/(Value) | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field |
| Message Type | 1 | 1 | 0xAD | `Auction Notification` Message |
| Time Offset | 2 | 4 | Time Offset | Nanosecond offset from last unit timestamp |
| Symbol | 6 | 6 | Printable ASCII | Symbol right padded with spaces. |
| Auction ID | 12 | 8 | Binary | Day specific identifier assigned to this auction. |
| Auction Type | 20 | 1 | Alphanumeric | `B` = AIM `S` = Solicitation Auction Mechanism `T` = Step Up Mechanism (SUM) `A` = SUM All or None |
| Side | 21 | 1 | Alphanumeric | "B" or "S" |
| Price | 22 | 8 | Binary Long Price | For SUM this will reflect the NBBO price of the opposite side of the auction at the time of entry. For AIM on EDGX, Price will be the auction start price. For SPX/SPXW AIM on C1, Price will be the auction start price, otherwise 0. For SAM, this will reflect the limit price specified on the order. |
| Contracts | 30 | 4 | Binary | Number of contracts available in the auction. |
| Customer Indicator | 34 | 1 | Alphanumeric | `N` = Non-Customer `C` = Customer |
| ParticipantID | 35 | 4 | Alphanumeric | Executing Broker (optional) of firm attributed to this quote |
| Auction End Offset | 39 | 4 | Binary | Nanosecond offset from last timestamp |
| Client ID | 43 | 4 | Alphanumeric | Optional user specified value attributed to this quote. |
| Total Length = 47 bytes |  |  |  |  |

### Auction Cancel

`Auction Cancel` messages are used to disseminate the cancellation of an earlier `Auction Notification` message as a result of a user cancellation of the original order, a user modification request to change the price or increase the original order quantity, or a fading of the NBBO.

A user request to modify the order price or to increase the original order quantity will result in a cancellation of the auction followed by a new `Auction Notification` message. `Auction Cancel` messages will not be issued for order quantity decrements.

**Table 1. Auction Cancel**

| Field Name | Offset | Length | Type/(Value) | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field |
| Message Type | 1 | 1 | 0xAE | `Auction Cancel` Message |
| Time Offset | 2 | 4 | Time Offset | Nanosecond offset from last unit timestamp |
| Auction ID | 6 | 8 | Binary | Day specific identifier assigned to this auction |
| Total Length = 14 bytes |  |  |  |  |

### Auction Trade

`Auction Trade` messages are used to disseminate executions resulting from an options auction.

**Table 1. Auction Trade**

| Field Name | Offset | Length | Type/(Value) | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field |
| Message Type | 1 | 1 | 0xAF | `Auction Trade` Message |
| Time Offset | 2 | 4 | Time Offset | Nanosecond offset from last unit timestamp |
| Auction ID | 6 | 8 | Binary | Day specific identifier assigned to this auction |
| Execution ID | 14 | 8 | Binary | Day specific identifier assigned to this execution |
| Price | 22 | 8 | Binary Long Price | Trade price |
| Contracts | 30 | 4 | Binary | Number of contracts traded |
| Total Length = 34 bytes |  |  |  |  |

### Options Auction Update

`Options Auction Update` messages are used to disseminate price and size information and Composite Market bid and offer prices during Opening and Re-Opening (halt) auctions on the Cboe Options Exchange. `Options Auction Update` messages are sent every five seconds during an opening period provided that one of the field values has changed. When no values have changed, a message is sent once every 60 seconds. Refer to the Cboe Titanium U.S. Options Opening Process for more information.

**Table 1. Options Auction Update**

| Field Name | Offset | Length | Type/(Value) | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field. |
| Message Type | 1 | 1 | 0xD1 | `Options Auction Update` Message |
| Time Offset | 2 | 4 | Time Offset | Nanosecond offset from last unit timestamp. |
| Symbol | 6 | 8 | Printable ASCII | Symbol right padded with spaces. |
| Auction Type | 14 | 1 | Alphanumeric | `G` = GTH Opening (C1 only) `O` = RTH Opening (C1 Only) `H` = Halt Re-Opening `V` = Volatility Opening |
| Reference Price | 15 | 8 | Binary Long Price | Collared VMIM price computed on the queuing book only. |
| Buy Contracts | 23 | 4 | Binary | Cumulative Buy contracts at the Reference Price and above. |
| Sell Contracts | 27 | 4 | Binary | Cumulative Sell contracts at the Reference Price and below. |
| Indicative Price | 31 | 8 | Binary Long Price | Collared VMIM price computed on the combined queueing book and the continuous book. Equal to Reference Price for options that do not have a GTH trading session. |
| Auction Only Price | 39 | 8 | Binary Long Price | Uncollared VMIM price computed on the queuing book only. |
| Opening Condition | 47 | 1 | Alphanumeric | `O` = Would open `Q` = Need quote to open `B` = Need more buyers (C1 Only) `S` = Need more sellers (C1 Only) `C` = Crossed Composite Market |
| Composite Market Bid Price | 48 | 8 | Binary Long Price | Bid Price of the prevailing Composite Market |
| Composite Market Offer Price | 56 | 8 | Binary Long Price | Offer Price of the prevailing Composite Market. |
| Total Length = 64 bytes |  |  |  |  |

### Auction Summary

`Auction Summary` messages are used to disseminate the results of the Opening and Re-Opening process. An Opening or Re-Opening `Auction Summary` message for each symbol is sent at the conclusion of the Opening or Re-Opening process and represents the Cboe opening price.

**Table 1. Auction Summary**

| Field Name | Offset | Length | Type/(Value) | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field. |
| Message Type | 1 | 1 | 0x96 | `Auction Summary` Message |
| Time Offset | 2 | 4 | Time Offset | Nanosecond offset from last unit timestamp. |
| Symbol | 6 | 8 | Printable ASCII | Symbol right padded with spaces. |
| Auction Type | 14 | 1 | Alphanumeric | `G` = GTH Opening (C1 Only) `O` = RTH Opening (C1 Only) `H` = Halt Re-Opening `V` = Volatility Opening |
| Price | 15 | 8 | Binary Long Price | Auction price. |
| Quantity | 23 | 4 | Binary | Cumulative number of contracts executed during the auction. |
| Total Length = 27 bytes |  |  |  |  |

### Width Update

The `Width Update` message is used to communicate opening quote width multiplier. This message will be sent in the event that the exchange decides to change the quote width multiplier on a per underlying basis. For complete details on the opening collars see the Cboe Titanium U.S. Options Opening Process.

**Table 1. Width Update**

| Field Name | Offset | Length | Type/(Value) | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field. |
| Message Type | 1 | 1 | 0xD2 | `Width Update` Message |
| Time Offset | 2 | 4 | Time Offset | Nanosecond offset from last unit timestamp. |
| Underlying | 6 | 8 | Printable ASCII | Underlying right padded with spaces. |
| Width Type | 14 | 1 | Alphanumeric | `R` = Regular `V` = Volatility |
| Multiplier | 15 | 4 | Multiplier | Width multiplier |
| Total Length = 19 bytes |  |  |  |  |

### Symbol Mapping

A `Symbol Mapping` message is used to map the 6 character multicast feed symbol field to an OSI symbol. These messages are sent continuously through the day at variable rates as bandwidth allows. Members who consume the Options Auction feed will be able to receive the full list of symbols in approximately 30 minutes.

**Table 1. Symbol Mapping**

| Field Name | Offset | Length | Type/(Value) | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field |
| Message Type | 1 | 1 | 0x2E | `Symbol Mapping` Message |
| Feed Symbol | 2 | 6 | Printable ASCII | Symbol right padded with spaces |
| OSI Symbol | 8 | 21 | Printable ASCII | OSI Symbol |
| Symbol Condition | 29 | 1 | Alphanumeric | `N` = Normal `C` = Closing Only |
| Underlying | 30 | 8 | Alphanumeric | Symbol of underlying instrument right padded with spaces. |
| Total Length = 38 bytes |  |  |  |  |

### End of Session

The `End of Session` message is sent for each unit when the unit shuts down. No more auction messages will be delivered for this unit, but heartbeats from the unit may be received.

**Table 1. End of Session**

| Field Name | Offset | Length | Type/(Value) | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field |
| Message Type | 1 | 1 | 0x2D | `End of Session` Message |
| Timestamp | 2 | 4 | Binary | Nanosecond offset from last unit timestamp. |
| Total Length = 6 bytes |  |  |  |  |

### SOQ Strike Range Update (C1 Only)

The `SOQ Strike Range Update` message is only available on the C1 Exchange. This message disseminates the minimum and maximum strike prices of the strike price range used to calculate the Special Opening Quote (SOQ) on a Volatility Settlement date. In the event that multiple distinct SOQ calculations occur on the same day, the applicable SOQ is differentiated by the SOQ Identifier field, which is set to the CSMi symbol on which the final settlement SOQ value is disseminated.

**Table 1. SOQ Strike Range Update**

| Field Name | Offset | Length | Type/(Value) | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field |
| Message Type | 1 | 1 | 0x9D | `SOQ Strike Range Update` Message |
| Time Offset | 2 | 4 | Time Offset | Nanosecond offset from last unit timestamp |
| SOQ Identifier | 6 | 20 | Printable ASCII | Dissemination symbol of the final SOQ right padded with spaces. |
| Lower Strike Price | 26 | 8 | Binary Long Price | SOQ lower strike price |
| Upper Strike Price | 34 | 8 | Binary Long Price | SOQ upper strike price |
| Total Length = 42 bytes |  |  |  |  |

### Constituent Symbol Mapping (C1 Only)

The `Constituent Symbol Mapping` message is only available on the C1 Exchange. This message is used to communicate which options series (if any) are Constituent Series in a Volatility Settlement Special Opening Quote (SOQ). The message is identical to the `Symbol Mapping` message with the addition of the SOQ Identifier field, which is set to the CSMi symbol on which the final settlement SOQ value is disseminated. The `Constituent Symbol Mapping` message is sent as an unsequenced message with one message sent for each Constituent Series in a continuous loop as bandwidth allows.

**Table 1. Constituent Symbol Mapping**

| Field Name | Offset | Length | Type/(Value) | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field |
| Message Type | 1 | 1 | 0x9E | `Constituent Symbol Mapping` Message. |
| Feed Symbol | 2 | 6 | Printable ASCII | Symbol right padded with spaces |
| OSI Symbol | 8 | 21 | Printable ASCII | OSI Symbol |
| Symbol Condition | 29 | 1 | Alphanumeric | `N` = Normal `C` = Closing Only |
| Underlying | 30 | 8 | Alphanumeric | Symbol of underlying equity right padded with spaces. |
| SOQ Identifier | 38 | 20 | Printable ASCII | Dissemination symbol of the final SOQ right padded with spaces. |
| Total Length = 58 bytes |  |  |  |  |

## Message Types

```
0xB1          Time Reference(C1 Only)
0x20          Time
0x97          Unit Clear
0xAD          Auction Notification
0xAE          Auction Cancel
0xAF          Auction Trade
0xD1          Options Auction Update
0x96          Auction Summary
0xD2          Width Update
0x2E          Symbol Mapping
0x2D          End of Session
0x9D          SOQ Strike Range Update
0x9E          Constituent Symbol Mapping
```

## Example Messages

Each of the following message types must be wrapped by a sequenced unit header. Note that in the following examples, each byte is represented by two hexadecimal digits.

### Sequenced Unit Header

| Hdr Length | 31 00 | 49 bytes, including header |
|---|---|---|
| Hdr Count | 02 | 2 messages to follow |
| Hdr Unit | 01 | Unit 1 |
| Hdr Sequence | 00 00 00 00 | Always set to zero |

### Time Reference (C1 Only)

**Table 1. Time Reference (C1 Only)**

| Length | 12 | 18 bytes |
|---|---|---|
| Type | B1 | Time Reference |
| Midnight Reference | D0 8B 34 60 | 2021-02-23 00:00:00 Eastern (1614056400 seconds since the Epoch) |
| Time | 00 E1 00 00 | 16:00:00 |
| Time Offset | 00 00 00 00 | Exactly 16:00:00 |
| Trade Date | 2F 62 34 01 | 20210223 February 23, 2021 |

### Time Message

**Table 1. Time Message**

| Length | 06 | 6 bytes |
|---|---|---|
| Type | 20 | Time |
| Time | 98 85 00 00 | 34,200 seconds =09:30 AM Eastern |

### Time Message

**Table 1. Time Message**

| Length | 0A | 10 bytes |
|---|---|---|
| Type | 20 | Time |
| Time | 98 85 00 00 | 34,200 seconds =09:30 AM Eastern |
| Epoch Time (C1 only) | 68 11 35 60 | 1,614,090,600 seconds since the Epoch |

### Unit Clear

**Table 1. Unit Clear**

| Length | 06 | 6 bytes |
|---|---|---|
| Type | 97 | Unit Clear |
| Time Offset | 18 D2 06 00 | 447,000 ns since last Time Message |

### Auction Notification Message

**Table 1. Auction Notification Message**

| Length | 2F | 47 bytes |
|---|---|---|
| Type | AD | Auction Notification |
| Time Offset | 18 D2 06 00 | 447,000 ns since last Time Message |
| Symbol | 30 30 6D 45 56 4F | 00mEVO |
| Auction ID | 05 40 5B 77 8F 56 1D 0B | 631WC4000005 |
| Auction Type | 54 | T = SUM |
| Side | 42 | B = Buy Side |
| Price | E8 A3 0F 00 00 00 00 00 | $102.50 |
| Contracts | 64 00 00 00 | 100 contracts |
| Customer Indicator | 43 | C = Customer |
| Participant ID | 45 46 49 44 | EFID |
| Auct. End Offset | 38 73 0E 00 | 947,000 ns since last Time Message |
| Client ID | 43 4C 49 44 | CLID |

### Auction Cancel Message

| Length | E | 14 bytes |
|---|---|---|
| Type | AE | Auction Cancel |
| Time Offset | 18 D2 06 00 | 447,000 ns since last Time Message |
| Auction ID | 05 40 5B 77 8F 56 1D 0B | 631WC4000005 |

### Auction Trade Message

**Table 1. Auction Trade Message**

| Length | 22 | 34 bytes |
|---|---|---|
| Type | AF | Auction Trade |
| Time Offset | 18 D2 06 00 | 447,000 ns since last Time Message |
| Auction ID | 05 40 5B 77 8F 56 1D 0B | 631WC4000005 |
| Execution Id | 34 2B 46 E0 BB 00 00 00 | 0AAP09VEC |
| Prc | E8 A3 0F 00 00 00 00 00 | $102.50 |
| Contracts | 64 00 00 00 | 100 contracts |

### Options Auction Update

**Table 1. Options Auction Update**

| Length | 40 | 64 bytes |
|---|---|---|
| Type | D1 | Options Auction Update |
| Time Offset | 18 D2 06 00 | 447,000 ns since last Time Message |
| Symbol | 30 30 6D 45 56 4F | 00mEVO |
| Auction Type | 56 | Volatility Opening |
| Reference Price | E8 A3 0F 00 00 00 00 00 | $102.50 |
| Buy Contracts | 64 00 00 00 | 100 Contracts |
| Sell Contracts | C8 00 00 00 | 200 Contracts |
| Indicative Price | E8 A3 0F 00 00 00 00 00 | $102.50 |
| Auction Only Price | E8 A3 0F 00 00 00 00 00 | $102.50 |
| Opening Condition | 4F | O = Would Open |
| Composite Market Bid Price | 50 69 0F 00 00 00 00 00 | $101.00 |
| Composite Market | 70 B7 0F 00 00 00 00 00 | $103.00 |

### Offer Price Auction Summary

**Table 1. Offer Price Auction Summary**

| Length | 1B | 27 bytes |
|---|---|---|
| Type | 96 | Auction Summary |
| Time Offset | 18 D2 06 00 | 447,000 ns since last Time Message |
| Symbol | 30 30 6D 45 56 5F 20 20 | 00mEVO |
| Auction Type | 4F | O = Opening |
| Price | E8 A3 0F 00 00 00 00 00 | $102.50 |
| Quantity | 4B 00 00 00 | 75 |

### Width Update

| Length | 13 | 19 bytes |
|---|---|---|
| Type | D2 | Width Update |
| Time Offset | 18 D2 06 00 | 447,000 ns since last Time Message |
| Underlying | 5A 56 5A 5A 54 20 20 20 | ZVZZT |
| Width Type | 52 | R = Regular |
| Multiplier | 0F 00 00 00 | Multiplier of 1.5 |

### Symbol Mapping Message

**Table 1. Symbol Mapping Message**

| Length | 26 | 38 bytes |
|---|---|---|
| Type | 2E | Symbol Mapping |
| Message Feed Symbol | 30 30 6D 45 56 4F | 00mEVO |
| OSI Symbol | 4D 53 46 54 20 20 31 39 30 39 32 30 43 30 30 31 35 30 30 30 30 | MSFT 190920C00150000 |
| Symbol Condition | 4E | ‘N’ - Closing Only |
| Underlying | 4D 53 46 54 20 20 20 20 | MSFT |

### End of Session

**Table 1. End of Session**

| Length | 06 | 6 bytes |
|---|---|---|
| Type | 2D | End of Session |
| Time Offset | 18 D2 06 00 | 447,000 ns since last Time Message |

### SOQ Strike Range Update (C1 Only)

| Length | 2A | 42 bytes |
|---|---|---|
| Type | 9D | SOQ Strike Range Update |
| Time Offset | 18 D2 06 00 | 447,000 ns since last Time Message |
| SOQ Identifier | 56 58 53 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | VXS |
| Lower Strike Price | 40 66 03 01 00 00 00 00 | $1,700 |
| Upper Strike Price | 00 48 E8 01 00 00 00 00 | $3,200 |

### Constituent Symbol Mapping (C1 Only)

**Table 1. Constituent Symbol Mapping (C1 Only)**

| Length | 3A | 58 bytes |
|---|---|---|
| Type | 9E | Constituent Symbol Mapping Message |
| Feed Symbol | 30 30 6D 45 56 4F | 00mEVO |
| OSI Symbol | 53 50 58 57 20 20 31 39 30 39 32 37 43 30 32 33 39 30 30 30 30 | SPXW 190927C02390000 |
| Symbol | 4E | ‘N’ - Normal |
| Condition | Underlying | SPX |
| SOQ Identifier | 56 58 53 20 20 20 20 20 56 58 53 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | VXS |

## Multicast Configuration

### US Options Production Environment Configuration

#### Limitations/Configurations

The following table defines Cboe current configuration for network and gap request limitations. These limitations are session based. Cboe reserves the right to adjust the gap request limitations to improve the effectiveness of the gap request infrastructure.

| Period/Type | Limit/Setting | Notes |
|---|---|---|
| MTU | 1500 | Cboe will send UDP messages up to 1500 bytes. Members should ensure that their infrastructure is configured accordingly. |
| Gig-Shaped Throttle | 1 Gb/s | The real-time and gap multicast head ends are configured to shape their output to this level to minimize packet loss. |

#### U.S. Options Unit/Product Distribution

| Unit | BZX/C1/C2/EDGX Symbol Range | Exceptions |
|---|---|---|
| 1 | A - AIPA~ |  |
| 2 | AIPB - AO~ |  |
| 3 | AP - AVGO~ |  |
| 4 | AVGP - BOIL~ |  |
| 5 | BOIM - CMPR~ | Excludes CBTX, CBTXW |
| 6 | CMPS - CSIQ~ |  |
| 7 | CSIR - DJTA~ |  |
| 8 | DJTB - FARO~ | Excludes DJX, DJXW |
| 9 | FARP - GLC~ |  |
| 10 | GLD - HAYW~ |  |
| 11 | HAYX - IYWA~ | Excludes IWM |
| 12 | IYWB - LMTA~ |  |
| 13 | LMTB - MES~ | Excludes MBTX, MBTXW |
| 14 | MET - MRM~ | Excludes MGTN, MGTNW |
| 15 | MRN - MSTR~ | Excludes MRUT |
| 16 | MSTS - NKEA~ | Excludes NANOS |
| 17 | NKEB - PDC~ | Excludes NVDA, OEX |
| 18 | PDD - RDDS~ | Excludes QQQ |
| 19 | RDDT - SEAA~ | Excludes RLG, RLV, RUI, RUT/RUTW |
| 20 | SEAB - SMHA~ | Excludes SIXB, SIXC, SIXE, SIXI, SIXR, SIXRE, SIXT, SIXU, SIXV, SIXY |
| 21 | SMHB - TEQ~ | Excludes SPEQX, SPESG, SPX/SPXW, SPY |
| 22 | TER - TTC~ | Excludes TSLA |
| 23 | TTD - VB~ | Excludes UKXM |
| 24 | VC - WYNN~ | Excludes VIX, VIXW |
| 25 | WYNO - Z~ | Excludes XEO, XSP, XSPBW |
| 26 | NVDA |  |
| 27 | TSLA |  |
| 28 | QQQ |  |
| 29 | IWM |  |
| 30 | SPY |  |

**Table 1. Units 31-35**

| Unit | BZX/C2 Symbol Range | C1 Symbol Range |
|---|---|---|
| 31 | DJX (C2 Only), DJXW (C2 Only), RUT (BZX and C2 Only), RUTW (C2 Only) | CBTX, CBTXW, DJX, DJXW, MBTX, MBTXW, MGTN, MGTNW, MRUT, OEX, RLG, RLV, RUI, RUT, RUTW, SIXB, SIXC, SIXE, SIXI, SIXR, SIXRE, SIXT, SIXU, SIXV, SIXY, SPEQX, SPESG, UKXM, XEO |
| 32 | N/A | NANOS, VIX, VIXW, XSP, XSPBW |
| 33 | N/A | SPX |
| 34 | N/A | SPXW |
| 35 | N/A | SPX/SPXW, Cross Product Spreads |

Note - Cboe reserves the right to add units and/or change symbol distribution with 48 hours of notice and no migration period. Notice will be given that the distribution will change on a certain date. Care should be taken to support mappings in these tables via software configuration.

#### C1 Options Production Multicast Routing Parameters

| Data Center | Rendezvous Point |
|---|---|
| Primary Data Center A feed | 74.115.128.183 |
| Primary Data Center B feed | 74.115.128.184 |
| Secondary Data Center E feed | 174.136.181.249 |

#### EDGX Options Production Multicast Routing Parameters

| Data Center | Rendezvous Point |
|---|---|
| Primary Data Center A feed | 74.115.128.160 |
| Primary Data Center B feed | 74.115.128.161 |
| Secondary Data Center E feed | 174.136.181.250 |

#### C1 Options Production Address/Unit Distribution

The following tables describe the unit distribution across the C1 Options Auction Feed.

| Primary Datacenter | Gig Shaped [CAA] 170.137.114.80/28 | Gig Shaped [CBA] 170.137.115.80/28 |  |
|---|---|---|---|
| Unit | IP Port | Real-time MC | Real-time MC |
| 1 | 30401 | 224.0.74.96 | 233.182.199.224 |
| 2 | 30402 |  |  |
| 3 | 30403 |  |  |
| 4 | 30404 |  |  |
| 5 | 30405 | 224.0.74.97 | 233.182.199.225 |
| 6 | 30406 |  |  |
| 7 | 30407 |  |  |
| 8 | 30408 |  |  |
| 9 | 30409 | 224.0.74.98 | 233.182.199.226 |
| 10 | 30410 |  |  |
| 11 | 30411 |  |  |
| 12 | 30412 |  |  |
| 13 | 30413 | 224.0.74.99 | 233.182.199.227 |
| 14 | 30414 |  |  |
| 15 | 30415 |  |  |
| 16 | 30416 |  |  |
| 17 | 30417 | 224.0.74.100 | 233.182.199.228 |
| 18 | 30418 |  |  |
| 19 | 30419 |  |  |
| 20 | 30420 |  |  |
| 21 | 30421 | 224.0.74.101 | 233.182.199.229 |
| 22 | 30422 |  |  |
| 23 | 30423 |  |  |
| 24 | 30424 |  |  |
| 25 | 30425 | 224.0.74.102 | 233.182.199.230 |
| 26 | 30426 |  |  |
| 27 | 30427 |  |  |
| 28 | 30428 |  |  |
| 29 | 30429 | 224.0.74.103 | 233.182.199.231 |
| 30 | 30430 |  |  |
| 31 | 30431 |  |  |
| 32 | 30432 |  |  |
| 33 | 30433 | 224.0.74.104 | 233.182.199.232 |
| 34 | 30434 |  |  |
| 35 | 30435 |  |  |

| Secondary Datacenter | Gig Shaped [CEA] 170.137.124.224/28 |  |
|---|---|---|
| Unit | IP Port | Real-time MC |
| 1 | 31401 | 233.19.3.176 |
| 2 | 31402 |  |
| 3 | 31403 |  |
| 4 | 31404 |  |
| 5 | 31405 | 233.19.3.177 |
| 6 | 31406 |  |
| 7 | 31407 |  |
| 8 | 31408 |  |
| 9 | 31409 | 233.19.3.178 |
| 10 | 31410 |  |
| 11 | 31411 |  |
| 12 | 31412 |  |
| 13 | 31413 | 233.19.3.179 |
| 14 | 31414 |  |
| 15 | 31415 |  |
| 16 | 31416 |  |
| 17 | 31417 | 233.19.3.180 |
| 18 | 31418 |  |
| 19 | 31419 |  |
| 20 | 31420 |  |
| 21 | 31421 | 233.19.3.181 |
| 22 | 31422 |  |
| 23 | 31423 |  |
| 24 | 31424 |  |
| 25 | 31425 | 233.19.3.182 |
| 26 | 31426 |  |
| 27 | 31427 |  |
| 28 | 31428 |  |
| 29 | 31429 | 233.19.3.183 |
| 30 | 31430 |  |
| 31 | 31431 |  |
| 32 | 31432 |  |
| 33 | 31433 | 233.19.3.184 |
| 34 | 31434 |  |
| 35 | 31435 |  |

Note - Cboe reserves the right to add multicast addresses with prior notice, but no migration period. Notice will be given that the distribution will change on a certain date. Care should be taken to support mappings in these tables via software configuration. Addresses in the gray area are pre-assigned but not available. Members should not configure their networks or systems for these addresses.

#### EDGX Options Production Address/Unit Distribution

The following tables describe the unit distribution across the EDGX Options Auction Feed.

| Primary Datacenter | Gig Shaped [EAA] 174.136.164.0/28 | Gig Shaped [EBA] 174.136.164.16/28 |  |
|---|---|---|---|
| Unit | IP Port | Real-time MC | Real-time MC |
| 1 | 30601 | 224.0.131.144 | 233.130.124.144 |
| 2 | 30602 |  |  |
| 3 | 30603 |  |  |
| 4 | 30604 |  |  |
| 5 | 30605 | 224.0.131.145 | 233.130.124.145 |
| 6 | 30606 |  |  |
| 7 | 30607 |  |  |
| 8 | 30608 |  |  |
| 9 | 30609 | 224.0.131.146 | 223.130.124.146 |
| 10 | 30610 |  |  |
| 11 | 30611 |  |  |
| 12 | 30612 |  |  |
| 13 | 30613 | 224.0.131.147 | 233.130.124.147 |
| 14 | 30614 |  |  |
| 15 | 30615 |  |  |
| 16 | 30616 |  |  |
| 17 | 30617 | 224.0.131.148 | 233.130.124.148 |
| 18 | 30618 |  |  |
| 19 | 30619 |  |  |
| 20 | 30620 |  |  |
| 21 | 30621 | 224.0.131.149 | 233.130.124.149 |
| 22 | 30622 |  |  |
| 23 | 30623 |  |  |
| 24 | 30624 |  |  |
| 25 | 30625 | 224.0.131.150 | 233.130.124.150 |
| 26 | 30626 |  |  |
| 27 | 30627 |  |  |
| 28 | 30628 |  |  |
| 29 | 30629 | 224.0.131.151 | 233.130.124.151 |
| 30 | 30630 |  |  |
| 31 | 30631 |  |  |
| 32 | 30632 |  |  |
| 33 | 30633 |  |  |

| Secondary Datacenter | Gig Shaped [EEA] 174.136.176.128/28 |  |
|---|---|---|
| Unit | IP Port | Real-time MC |
| 1 | 31601 | 233.19.3.128 |
| 2 | 31602 |  |
| 3 | 31603 |  |
| 4 | 31604 |  |
| 5 | 31605 | 233.19.3.129 |
| 6 | 31606 |  |
| 7 | 31607 |  |
| 8 | 31608 |  |
| 9 | 31609 | 233.19.3.130 |
| 10 | 31610 |  |
| 11 | 31611 |  |
| 12 | 31612 |  |
| 13 | 31613 | 233.19.3.131 |
| 14 | 31614 |  |
| 15 | 31615 |  |
| 16 | 31616 |  |
| 17 | 31617 | 233.19.3.132 |
| 18 | 31618 |  |
| 19 | 31619 |  |
| 20 | 31620 |  |
| 21 | 31621 | 233.19.3.133 |
| 22 | 31622 |  |
| 23 | 31623 |  |
| 24 | 31624 |  |
| 25 | 31625 | 233.19.3.134 |
| 26 | 31626 |  |
| 27 | 31627 |  |
| 28 | 31628 |  |
| 29 | 31629 | 233.19.3.135 |
| 30 | 31630 |  |
| 31 | 31631 |  |
| 32 | 31632 |  |
| 33 | 31633 |  |

Note - Cboe reserves the right to add multicast addresses with prior notice, but no migration period. Notice will be given that the distribution will change on a certain date. Care should be taken to support mappings in these tables via software configuration. Addresses in the gray area are pre-assigned but not available. Members should not configure their networks or systems for these addresses.

### US Options Certification Environment Configuration

#### U.S. Options Unit/Product Distribution

| Unit | BZX/C1/C2/EDGX Symbol Range | Exceptions |
|---|---|---|
| 1 | A - AIPA~ |  |
| 2 | AIPB - AO~ |  |
| 3 | AP - AVGO~ |  |
| 4 | AVGP - BOIL~ |  |
| 5 | BOIM - CMPR~ | Excludes CBTX, CBTXW |
| 6 | CMPS - CSIQ~ |  |
| 7 | CSIR - DJTA~ |  |
| 8 | DJTB - FARO~ | Excludes DJX, DJXW |
| 9 | FARP - GLC~ |  |
| 10 | GLD - HAYW~ |  |
| 11 | HAYX - IYWA~ | Excludes IWM |
| 12 | IYWB - LMTA~ |  |
| 13 | LMTB - MES~ | Excludes MBTX, MBTXW |
| 14 | MET - MRM~ | Excludes MGTN, MGTNW |
| 15 | MRN - MSTR~ | Excludes MRUT |
| 16 | MSTS - NKEA~ | Excludes NANOS |
| 17 | NKEB - PDC~ | Excludes NVDA, OEX |
| 18 | PDD - RDDS~ | Excludes QQQ |
| 19 | RDDT - SEAA~ | Excludes RLG, RLV, RUI, RUT/RUTW |
| 20 | SEAB - SMHA~ | Excludes SIXB, SIXC, SIXE, SIXI, SIXR, SIXRE, SIXT, SIXU, SIXV, SIXY |
| 21 | SMHB - TEQ~ | Excludes SPEQX, SPESG, SPX/SPXW, SPY |
| 22 | TER - TTC~ | Excludes TSLA |
| 23 | TTD - VB~ | Excludes UKXM |
| 24 | VC - WYNN~ | Excludes VIX, VIXW |
| 25 | WYNO - Z~ | Excludes XEO, XSP, XSPBW |
| 26 | NVDA |  |
| 27 | TSLA |  |
| 28 | QQQ |  |
| 29 | IWM |  |
| 30 | SPY |  |

**Table 1. Units 31-35**

| Unit | BZX/C2 Symbol Range | C1 Symbol Range |
|---|---|---|
| 31 | DJX (C2 Only), DJXW (C2 Only), RUT (BZX and C2 Only), RUTW (C2 Only) | CBTX, CBTXW, DJX, DJXW, MBTX, MBTXW, MGTN, MGTNW, MRUT, OEX, RLG, RLV, RUI, RUT, RUTW, SIXB, SIXC, SIXE, SIXI, SIXR, SIXRE, SIXT, SIXU, SIXV, SIXY, SPEQX, SPESG, UKXM, XEO |
| 32 | N/A | NANOS, VIX, VIXW, XSP, XSPBW |
| 33 | N/A | SPX |
| 34 | N/A | SPXW |
| 35 | N/A | SPX/SPXW, Cross Product Spreads |

Note - Cboe reserves the right to add units and/or change symbol distribution with 48 hours of notice and no migration period. Notice will be given that the distribution will change on a certain date. Care should be taken to support mappings in these tables via software configuration.

#### Options Certification Multicast Routing Parameters

| Primary Certification Data Center | Rendezvous Point |
|---|---|
| C1 | 74.115.128.131 |
| EDGX | 74.115.128.129 |

#### C1 Options Certification Address/Unit Distribution

The following tables describe the unit distribution across certification C1 Options Multicast Auction Feed out of the Primary datacenter.

| Primary Datacenter | WAN-Shaped 170.137.126.16/28 |  |
|---|---|---|
| Unit | IP Port | Real-time MC |
| 1 | 32401 | 233.103.126.22 |
| 2 | 32402 |  |
| 3 | 32403 |  |
| 4 | 32404 |  |
| 5 | 32405 |  |
| 6 | 32406 |  |
| 7 | 32407 |  |
| 8 | 32408 |  |
| 9 | 32409 |  |
| 10 | 32410 |  |
| 11 | 32411 |  |
| 12 | 32412 |  |
| 13 | 32413 |  |
| 14 | 32414 |  |
| 15 | 32415 |  |
| 16 | 32416 |  |
| 17 | 32417 | 233.103.126.23 |
| 18 | 32418 |  |
| 19 | 32419 |  |
| 20 | 32420 |  |
| 21 | 32421 |  |
| 22 | 32422 |  |
| 23 | 32423 |  |
| 24 | 32424 |  |
| 25 | 32425 |  |
| 26 | 32426 |  |
| 27 | 32427 |  |
| 28 | 32428 |  |
| 29 | 32429 |  |
| 30 | 32430 |  |
| 31 | 32431 |  |
| 32 | 32432 |  |
| 33 | 32433 |  |
| 34 | 32434 |  |
| 35 | 32435 |  |

Note - Cboe reserves the right to add multicast addresses with prior notice, but no migration period. Notice will be given that the distribution will change on a certain date. Care should be taken to support mappings in these tables via software configuration.

#### EDGX Options Certification Address/Unit Distribution

The following tables describe the unit distribution across certification EDGX Options Multicast Auction Feed out of the Primary datacenter.

| Primary Datacenter | WAN-Shaped 174.136.174.176/28 |  |
|---|---|---|
| Unit | IP Port | Real-time MC |
| 1 | 32601 | 224.0.74.208 |
| 2 | 32602 |  |
| 3 | 32603 |  |
| 4 | 32604 |  |
| 5 | 32605 |  |
| 6 | 32606 |  |
| 7 | 32607 |  |
| 8 | 32608 |  |
| 9 | 32609 |  |
| 10 | 32610 |  |
| 11 | 32611 |  |
| 12 | 32612 |  |
| 13 | 32613 |  |
| 14 | 32614 |  |
| 15 | 32615 |  |
| 16 | 32616 |  |
| 17 | 32617 | 224.0.74.210 |
| 18 | 32618 |  |
| 19 | 32619 |  |
| 20 | 32620 |  |
| 21 | 32621 |  |
| 22 | 32622 |  |
| 23 | 32623 |  |
| 24 | 32624 |  |
| 25 | 32625 |  |
| 26 | 32626 |  |
| 27 | 32627 |  |
| 28 | 32628 |  |
| 29 | 32629 |  |
| 30 | 32630 |  |
| 31 | 32631 |  |
| 32 | 32632 |  |
| 33 | 32633 |  |

Note - Cboe reserves the right to add multicast addresses with prior notice, but no migration period. Notice will be given that the distribution will change on a certain date. Care should be taken to support mappings in these tables via software configuration.

## Connectivity

### Supported Extranet Carriers

The Cboe Options Auction Feed will be made available to Members through extranet carriers that have completed their multicast implementation and certified with Cboe on a per-market basis. Cboe has certified a number of carriers for redistribution of Cboe Multicast data feeds as outlined in the Cboe Titanium U.S. Equities/Options Connectivity Manual. For more information on receiving the Cboe Options Auction Feed through any of these providers, please refer to the vendor contact information noted in the Extranet Providers section of the Connectivity Manual.

## References

For more information on Cboe Symbology, please refer to the Cboe Titanium U.S. Symbology Reference.

## Support

Please direct questions or comments regarding this specification to tradedesk@cboe.com.

## Revision History

| Document Version | Date | Description |
|---|---|---|
| 1.0.0 | 05/17/16 | Initial version 1.0.0. |
| 1.0.1 | 05/31/16 | Added Ips and Port Numbers to the EDGX Options Certification Address/Unit Distribution table. |
| 1.0.2 | 06/28/16 | Added Ips and Port Numbers to the EDGX Options Production Address/Unit Distribution table. Updated the `Sequenced Unit Header` to 8 bytes. Removal of NBBO Price from `Auction` `Notification` message. |
| 1.0.3 | 08/01/16 | Added support for BAM Auctions. |
| 1.0.4 | 01/06/17 | Updated description of `Auction Trade` message. |
| 1.0.5 | 10/17/17 | Cboe branding/logo changes. |
| 1.0.6 | 03/08/18 | Updated Unit Distribution ranges. |
| 1.0.7 | 03/23/18 | Updated Unit Distribution ranges effective date updated to 4/14/18. |
| 1.0.8 | 6/28/2018 | Added Multicast Options Auction Feed Descriptions table. Added Feed Connectivity Requirements section. Added feed shaping information to source network headers. |
| 1.1.0 | 11/16/18 | Added support for C1 Options Feed. |
| 1.1.1 | 12/06/18 | Added notes indicating Feature Pack 4 updates. |
| 1.1.2 | 03/07/19 | Added matching engine unit 33 information in support of XSP trading on EDGX Options effective 04/08/19. Added C1 certification primary data center rendezvous point IP address, unit distribution, and C1 Certification symbol ranges. |
| 1.1.3 | 04/05/19 | Correction to EDGX Options Gig Shaped EAA, EBA and EEA Feeds for Unit 33 |
| 1.1.4 | 04/15/19 | Added Production IP addresses for C1 Options. |
| 1.1.5 | 05/01/19 | Added notes indicating `Options Auction Update`, `Auction Summary`, and `Width Update` messages will be disseminated for EDGX options, effective with C1 Feature Pack 7. |
| 1.1.6 | 05/14/19 | Corrected description of `Width Update` message to indicate that message is only sent in the event that baseline MCW and OCW values are modified from their original state. Updated `Options Auction Update` message with Opening Condition = C (Crossed Composite Market), and addition Composite Market Bid and Offer price fields. Added `SOQ Strike Range Update` message. Update example for `Options Auction Update` and added example for `SOQ Strike Range` messages. Added additional proprietary products to matching unit 31 in C1. |
| 1.1.7 | 05/20/19 | Added `Constituent Symbol Mapping` message with example. |
| 1.1.8 | 06/12/19 | Corrected certification and production C1 symbol range for units 9 and 20. |
| 1.1.9 | 07/12/19 | Updated `Symbol Mapping` mapping description to indicate that full list of symbols should be received in approximately 30 minutes. |
| 1.1.10 | 7/25/19 | Added notes indicating `Options Auction Update` message Opening Condition values ‘B’ and ‘S’ are only applicable to the Cboe Options Exchange ("C1"). |
| 1.1.11 | 9/18/19 | Corrected `Symbol Mapping Message` and `Constituent Symbol Mapping` examples. |
| 1.1.12 | 1/31/20 | Corrected UKXM and QQQ symbol entries in Unit Distribution table. Clarified description of `Time` message. Updated SAM effective date for EDGX to 2/3/20. |
| 1.1.13 | 8/27/20 | Added SPESG to the Unit Symbol Distribution tables for C1 unit 31 (effective 09/21/20). |
| 1.1.14 | 10/06/20 | Added SPESG to the Unit Symbol Distribution table Exclusion entries for C1. |
| 1.1.15 | 10/20/20 | Removed XSP from the Unit Symbol Distribution tables on EDGX (effective 11/2/20). |
| 1.1.16 | 01/22/21 | Updated Price field description on `Auction Notification` message to indicate that for SPX and SPXW AIM, this field will reflect the auction price (C1 Only) (effective 02/22/21). |
| 1.1.17 | 02/01/21 | Added MRUT to the Unit/Product Distribution tables for C1 unit 31 (effective 3/01/21). Added new updated Unit/Product Distribution tables with harmonized symbol ranges (effective 3/22/21). |
| 1.1.18 | 03/25/21 | Added Binary Date field type to Section 2.2 - Data Types (effective 10/10/21 TBD 09/27/21 Q3 2021 ). Added new `Time Reference` message (effective 10/10/21 TBD 09/27/21 Q3 2021 ). Added EpochTime field to `Time` message (effective 10/10/21 TBD 09/27/21 Q3 2021 ). Updated description of Auction Type field on `Options Auction Update` and `Auction Summary` messages ( effective TBD 09/27/21 Q3 2021 ). |
| 1.1.19 | 05/13/21 | Updated Curb session effective date to TBD 09/27/21. |
| 1.1.20 | 08/25/21 | Updated Curb session effective date to TBD. |
| 1.1.21 | 09/09/21 | Updated description of Auction Type field on `Options Auction Update` and `Auction Summary` messages (effective TBD). |
| 1.1.22 | 09/30/21 | Updated effective date for new `Time Reference` message (C1 Only) , EpochTime field to `Time` message (C1 Only) , and Binary Date field type to Section 2.2 - Data Types to 10/10/21. Added new section 1.1 - '24x5 Feed Hours and System Restart (C1 Only) ' (effective 10/10/21). |
| 1.1.23 | 11/04/21 | Corrected example `Time` message values. Removed note indicating Auction Type = `O` will be sent prior to Curb session. This value will only be sent for the RTH Opening. |
| 1.1.24 | 02/02/22 | Added NANOS to the C1 unit 32 Unit/Product Distribution tables (effective 03/14/22). |
| 1.1.25 | 03/01/22 | Removed XSP from the BZX unit 31 Unit/Product Distribution tables. |
| 1.1.26 | 11/07/22 | Moved XSP to the C1 unit 32 Unit/Production Distribution tables (effective 12/04/22). |
| 1.1.27 | 03/30/23 | Clarified RUT is on BZX and C2 Unit 31. |
| 1.1.28 | 08/21/23 | Updated Price in AIM `Auction Notification` messages. |
| 1.1.29 | 01/29/24 | Added MXACW, MXUSA, and MXWLD to the C1 unit 31 Unit/Product Distribution tables (effective 03/18/24). |
| 1.1.30 | 11/22/24 | Added CBTX, CBTXW, MBTX, and MBTXW to the C1 unit 31 Unit/Product Distribution tables (effective 12/02/24). |
| 1.1.31 | 12/13/24 | Added new Unit/Product Distribution for Units 1-30 (effective 03/31/25). |
| 1.1.32 | 01/15/25 | Updated with Cboe Titanium branding. |
| 1.1.33 | 03/25/25 | Added SPEQX to C1 unit 31 unit/product distribution (effective 04/14/25). |
| 1.1.34 | 07/08/25 | Added Time Offset data type. Effective 09/08/25, Time Offset fields will be populated to nanosecond precision. |
| 1.1.35 | 10/20/25 | Added MGTN and MGTNW to unit 31 in US Options Unit/Product Distribution and excluded MGTN and MGTNW from unit 14 (effective 12/08/25 TBD 11/17/25). |
| 1.1.36 | 11/06/25 | Updated MGTN and MGTNW effective dates to TBD. |
| 1.1.37 | 11/18/25 | Updated MGTN and MGTNW effective dates to 12/08/25. |
| 1.1.38 | 01/12/26 | Updated 24x5 Feed Hours and System Restart to document the new time at which persisted orders are added back into the order book (effective 02/02/26). |
| 1.1.39 | 04/01/26 | Removed references to MXEA, MXEF, MXACW, MXUSA, and MXWLD. Updated Time description in `Time` and `Time Reference` messages. Added XSPBW to C1 unit 32 Unit/Product Distribution tables (effective 06/15/26 06/01/26 ). |
| 1.1.40 | 05/14/26 | Updated XSPBW effective date to 06/15/26. Updated U.S. Options Unit/Product Distribution to include DJXW (effective 05/18/26). |
| 1.1.41 | 07/21/26 | Removed VIX and VIXW exclusion from unit 23 and added VIX and VIXW exclusion to unit 24 U.S. Options Unit/Product Distribution tables. |