What does "Closing Run Logic" mean in the fixspec for the real-time feed, and how does it affect the behavior of that field?
For some fields it is set to "Clear" (e.g. under FID:6 TRDPRC_1) and for others it is set to "Does not clear"?
The Closing Run occurs each trading day and occurs at a specific time as defined by the exchange and feed. The time varies across feed but will typically occur outside of the trading hours. The logic is exchange-specific but in general, many of the fields within that feed are set or reset. Each exchange will define their own logic as outlined within the fixspec. For example, in some feeds, the closing price is copied over from the FID 6 - TRDPRC_1 and then the TRDPRC_1 value is cleared. Where other fields will never change or clear - such as the Exchange ID or Currency.
The run will publish out the changes to downstream applications that have open subscriptions to these items. The downstream applications will need to account for these updates.