The corresponding link is at http://msdn.microsoft.com/en-us/library/dd465326(VS.100).aspxIt is for web.config but I want to apply it in app.config.I want to use Transform attribute. My question is that where should I place it?Sample file:\[code\]<?xml version="1.0" encoding="utf-8"?><configuration> <appSettings> .... </appSettings> <connectionStrings> <add name="..."> </connectionStrings><system.serviceModel><services><service behaviorConfiguration="GenericServiceBehavior" name="GenericServiceContractIm"> <endpoint ...> </endpoint> </service></services><bindings> <basicHttpBinding> <binding name="..."> <security mode="None"> <transport clientCredentialType="None" proxyCredentialType="None" realm="" /> <message clientCredentialType="UserName" algorithmSuite="Default" /> </security> </binding> <behaviors> <serviceBehaviors> <behavior name="GenericServiceBehavior"> <serviceTimeouts transactionTimeout="00:09:10" /> <serviceThrottling maxConcurrentCalls="20" maxConcurrentSessions="20" maxConcurrentInstances="20" /> <!--//TODO: test this--> <serviceDebug includeExceptionDetailInFaults="true" /> <serviceMetadata /> </behavior> </serviceBehaviors></behaviors><client> </client></system.serviceModel><system.web> </system.web></configuration>\[/code\]If I want replace multiple values in different sections, is one Transform attribute in the root enough?Also if I have mulitiple config files, do I have to add xdt:Transform in every file or just one file say app.Debug.config?