In GNU/Linux, SPSS does not handle mime type files, whereas in MS Windows the files are different. SAV files are recognized as "SPSS Statistics" and ZSAV files as "SPSS
Statistics Compressed" (both with different icons).
However, I could not find information specific mime type in "regedit". Keep looking, maybe another user may have more luck.
Regards
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Bastián Díaz
I've been unable to find out how SPSS handles this through web
searches. I would appreciate it if someone with SPSS would report
whether SPSS uses different mime types for .sav and .zsav files (and
if so, what MIME types those are).