I concur. As not everyone has the newest version, new versions have enough backwards compatibility to read the older formats, and often to write to them as well.
With MS Office, .xls
is the format that is pretty much universal. Practically every office suite can read and write .xls
. While the newer versions of MS Office default to .xlsx
, those files are only safely readable by those with new versions of Office; trying to open them with older versions may be beyond the skills of the average person (a few hoops to jump through), and those like me who use non-Microsoft office software will either have similar difficulties or just plain be unable to read the .xlsx
file.
Using .xls
will avoid any of those problems.
It may also be called “Excel 97/2000/XP/2003” format instead, and most computers are set up to hide the extension of known file types.