Route events with an Amazon EventBridge rule

You're a developer at an online retailer whose app publishes events to Amazon EventBridge. The fulfillment team needs to receive only the OrderPlaced events (source orders.service) and ignore everything else on the bus, so you create a rule with an event pattern matching source orders.service and detail-type OrderPlaced, and add an SQS queue as the target.

What determines whether a given event on the bus is forwarded to that queue?