Re: Ask someone working in any field
The difficult formats are the proprietary binaries other than word processing. Word processing formats usually have the raw text inside in ASCII or similar well-known representation, so reverse-engineered conversion utils are usually available - even if they only get the text, it's still worthwhile.
However, once you look at other fields you will find many obsolete and difficult formats.
For example: Strand SSF - have to convert to Ascii, using an unsupported and difficult to find Win 95 application called Showport. As far as I know the source code for that program is long gone.
If Strand hadn't written that before going bankrupt then a lot of people would have lost a lot of data.