This message includes the full market data state for a single instrument. It can be sent in response to a Market Data Request <35=V> or can be unsolicited. If sent in response to a request, it should include the relevant MDReqID (262).

Multiple snapshots can potentially be used to provide updates in a subscription workflow, instead of Market Data Incremental Refresh <35=X>. In that case, each snapshot fully replaces the previous one. This potentially simplifies processing at the cost of additional bandwidth.

This message includes many optional fields. Firms can individually decide which optional fields they wish to support.