Muwhahahahahahahaha.

True client story: I was once required to fill out opex/capex split timesheets into an Excel spreadsheet once a month, for each of my teams.

The spreadsheet came with instructions containing dire warnings that changing the formatting would change the semantic meaning of some of the cells, thereby breaking the spreadsheet for everyone.

I'm pretty sure that the developers of that spreadsheet used cell formatting to encode metadata about the cell values.