The client and the exchange transmit the Heartbeat <0> message to verify connectivity during periods of inactivity. The exchange will send a Heartbeat anytime it has not transmitted a message during the heartbeat interval. The client is expected to employ the same logic.
| Tag | Field Name | Data Type | Req’d | Comments |
|---|---|---|---|---|
| Standard header | Y | MsgType 35=0 | ||
| 112 | TestReqID | string | C | Identifier to be returned in resulting Heartbeat if requested from a TestRequest. |
| Standard trailer | Y |