Hi Roland,
As Chris mentioned, this is used when the App is deployed using the "Merge Files" option (Toolkit > configure > Application profile > Mics Settings > Performance settings). In this case, the file f* without file extension will be generated. If you didn’t used this option, please ignore this section.
https://docs.appeon.com/appeon_online_help/pb2019r2/powerserver_toolkit_user_guide/ch03s02s01.html#MiscSettings
By default, the Web server running on IIS 7.5 or later versions does not allow the following two types of files to be downloaded to a browser:
1 Files with file extension, but not specified in IIS.
2 Files without file extension.
Therefore, you would need to explicitly define these file types in IIS. Please refer to the article below for details:
https://docs.appeon.com/appeon_online_help/ps2019/appeon_troubleshooting_guide/ch04s01s03.html
Regards,
ZhaoKai