I have a few sets (6) of more than 50 rar files in 1 folder.
All having close to the same name, only the extensions are different
DO shows this this little 'RAR-symbol' in front of each file.
Only upto r29 ...
As from r30 it shows the 'unknown' symbol (i.e. one as if the file is not associated with anything).
The RAR files are okay - can be un-rarred no problem.
This is with all the 6 set, i.e. each time r30 shows this unknown
This is nothing to do with Opus itself. Whatever created your RAR filetype only went up to .r29 in the extensions it associated with the RAR filetype.
You can use the Opus filetype editor to add .r30 to .r99 if you want to. Or, when creating split RAR archives, use the option which names them .partXX.rar so that all the files have a .RAR extension. Or not worry about it since you never need to double-click anything but the base .rar file.
I checked out PowerArchiver and indeed found the last file associated with RAR was/is .R29 ...
Thanks for the tip.