In the uploaded pictures from my mobile phone, I get a line with the following information: Interoperability Index = R98? What is this Index?
Quote from www.exif.org/dcf.PDF (Design rule for Camera File system):
Basically it's a set of rules for the file names, directory structure and mandatory meta-data for digital camera so that all compatible viewers and printer will be able to read the memory cards of all compatible cameras.
All cameras that are compatible with ExifR98 are required to add the interoperability index tag to the EXIF data with the value "R98" (among other things).