The document discusses how to use the request-reply scope in Mule applications. The request-reply scope allows embedding asynchronous processing within a synchronous Mule flow. It receives a response from an asynchronous flow without hardcoding the destination. The document provides an example Mule flow configuration that uses request-reply scope to convert a one-way VM flow to a request-response flow. The flow demonstrates setting a payload in the request flow, passing it asynchronously to the reply flow which modifies the payload and returns it synchronously.