Epson Perfection V750 and V850 come with SilverFast SE Plus and additional software from X-Rite and targets for IT8 calibration.
What if you've upgraded your scanning software to Ai Studio and now want to use its superior calibration feature with the targets from X-Rite? 

As these targets are lacking a barcode like those from LaserSoft Imaging, SilverFast Ai Studio has no handle to identify what reference file is to be used with the target. It will ask the user what it to be used. 

You can download the reference files for your targets from the X-Rite's website: https://www.xrite.com/de/service-support/downloads/m/monaco-it8-reference-files

SilverFast Ai Studio can of course use standard IT8 format text files for calibration. 
Most of the reference files downloaded from above link are already in TXT form. The can directly be used an understood by SilverFast's calibration routine. 

Some older files though carry the MRF extension. While these are essentially RAR compressed TXT files, you will need to uncompressed them for before you can make use of these. 

On Windows, we suggest to install the (free to use) "7-ZIP" (GNU open source) extracting utility. 
Download available from: https://7-zip.org/
Then simply rename MRF to RAR, and unpack the that file to get the original reference TXT file back for your IT8 calibration purpose. 

On macOS the free tool "The Unarchiver" (https://theunarchiver.com/) will provide you the same ability. 

On both both platforms, we suggest to add the ".txt" extension to the resulting file, then you will finally be able to successfully run the IT8 calibration in SilverFast Ai Studio.