Sending you an upload link...
i only just learned that indesign isn't backwards compatible.
InDesign is not forwards compatible: any version of it cannot read files created with newer ones.
That's nothing to be amazed about. Most software is not forwards compatible, I only know of one exception, and that is Microsoft Word.
InDesign is backwards compatible all the way to CS (v.3) at least -- the modern vsns of InDesign should still be able to read those files.