[This is preliminary documentation and subject to change.]
The /app_config switch selects application-configuration mode, which allows you to use some ACF keywords in the IDL file. With this MIDL compiler switch, you can omit the ACF and specify an interface in a single IDL file.
Missing <remarks> documentation for P:NAnt.VisualCpp.Tasks.MidlTask.AppConfig
MidlTask Class | NAnt.VisualCpp.Tasks Namespace