You would typically use a library like libarchive or sharpcompress to programmatically identify , verify , or extract multi-volume archives.
While I’ve assumed you’re likely trying to or manage these game files, it's also possible you are looking for a feature list of what is included in the Extended Edition itself. Partisans.1941.Extended.Edition-PLAZA.part2.rar
If you are a developer trying to write a script or "feature" that handles these types of files: You would typically use a library like libarchive