Reports emerged this week of a problem for Apple users opening presentation files created in Keynote. The latest update of Keynote -- in fact, all of iWork '13 -- won't open files created with versions before iWork '09, instead prompting users to find a copy of iWork '09 and open the file with that.
If a user has simply upgraded to iWork '13 from '09, the old version is still archived on the computer and can be used to open the file (look in
/Applications/iWork '09/). But people who haven't upgraded and thus don't have the older iWork '09 version also installed -- say, because they are at work accessing files created at home -- would indeed be unable to open older files. Worse, once you've opened old files in iWork '13, they will no longer work in the old versions.
Even if there's currently a workaround for some users (iWork '13 has an export option to create iWork '09 files), there probably won't be one forever, because that's clearly not Apple's priority. This is a serious red flag for users of iWork. It demonstrates three important truths.
First, the file format used by the software is considered transient by Apple. The company can and will change it any time, in any way, without warning and without regard to the consequences. Second, work created with this software should be considered unsuitable for archiving. When you need to refer back to a presentation or document in five years, there is a strong possibility you won't be able to open it reliably. Third, Apple's priorities are not the same as yours. According to the Verge, Apple made these changes to iWork for easier compatibility with the newest versions of its mobile platform iOS at the known expense of backward compatibility on the Mac.
The problem of bit rot is as old as the software application. It is part of a family of problems caused when the software that manages your data is not under your ultimate control. Another manifestation is "interoperability" -- trying to use data created in one application in an equivalent alternative created by a different vendor. Yet another is decayed digital restrictions, where the DRM used by a vendor for an defunct business model continues to defeat legal access by the owner of the data.
This last problem is especially toxic as the DMCA actually makes it a crime to access your own data if to do so you have to break into the defunct DRM. All three are used as a tool to lock-in customers and lock-out competitors, at the cost of customer flexibility.
I've encountered these problems repeatedly in my career. I've used CTOS Word Processor, IBM DisplayWrite, WordPerfect, Ami Pro, PagePlus, and Microsoft Office -- and in each case run into problems opening files in later versions.
Back in the 1980s I had to write a software system to cure an interoperability issue with IBM DisplayWrite and other word processors. In the '90s I faced problems getting Ami Pro files into Microsoft Word and getting PagePlus files into pretty much anything else. In the last decade I found Microsoft Word documents from new versions on Windows not opening in the version I was running on the Mac. The news that Apple too is messing with file formats and eliminating the ability to access archived files is not too surprising.