Q: What must I do to trigger Autorun on my USB storage device?
The Autorun capabilities are restricted to CD-ROM drives and fixed disk drives. If you need to make a USB storage device perform Autorun, the device must not be marked as a removable media device and the device must contain an Autorun.inf file and a startup application.

The removable media device setting is a flag contained within the SCSI Inquiry Data response to the SCSI Inquiry command. Bit 7 of byte 1 (indexed from 0) is the Removable Media Bit (RMB). A RMB set to zero indicates that the device is not a removable media device. A RMB of one indicates that the device is a removable media device. Drivers obtain this information by using the StorageDeviceProperty request.

For more information about the SCSI Inquiry command, see the T10 committee located at http://www.t10.org. This link leaves the Microsoft.com site

For more information about the StorageDeviceProperty, see the STORAGE_DEVICE_DESCRIPTOR storage structure in the Windows DDK, located at http://msdn.microsoft.com/library/default.asp?url=/library/en-us/storage_r/hh/storage_r/structs-general_3c393126-f5c8-47d8-bfb5-6127ce656e9a.xml.asp.

For more information on Autorun.inf files see the "Creating an AutoRun-Enabled Application" article located at http://msdn.microsoft.com/library/default.asp?url=/library/en-us/shellcc/platform/shell/programmersguide/shell_basics/shell_basics_extending/autorun/autoplay_works.asp?frame=true.