The conventional wisdom is that when you store data for long-term storage, you convert the data into a format that will last for decades. It should be in NTFS or FAT and the file format should be one in which will be around for decades.
For example, they do not recommend that files should be left in docx (Word format) because you don't now if Microsoft will be around 10 years from now. They suggest that formats such as txt.
HOWEVER, I have most of my documents in Microsoft Word and Excel. And, the formatting of the document is extremely important to me. It allows readability of the document. It's critical. If it's all in the same regular text, it makes it impossible to read.
What do you people suggest that I should do? I want to burn my long-term files but what format do you recommend that I should save it in on my blu-ray M-discs?