...but it cannot "really" be edited.
i would like to know how institutions does this. they surely have archived microsoft office documents. does opening an e.g. office 2000 file open without changing the format and document styles?
My understanding is that opening any Word Processor document (not just MS Word files) can be an issue as far as formatting is concerned.
If the document used fonts no longer available on the computer, the system will substitute another font. While it may look very similar, line breaks and page breaks could shift - causing formatting issues.
Often documents are formatted for a specific printer. Unless the system has access to the same printer, the document may format differently.
If the document uses complex formatting, the creator may have used undocumented - and subsequently discontinued - features. Or features that have had their behaviour changed in newer releases of the application. For instance, building tables. If it is just a plain grid, then there shouldn't be any issues. But once you start merging and joining cells the formatting can be difficult to maintain across SW generations.
etc etc
Maintaining archives of old documents is a huge and complex field. National archives, for example, often maintain very old computers so that they can run very old applications, in order to access documents that are really not that old.
Meanwhile, in Timbuktu, they recently smuggled out over a quarter of million manuscripts to keep them safe from the rebels. Books and parchments that are up to 900 years old. While we have issues keeping a 15 year old Word document safe. sigh....