You are correct that a document from ECMA is expected to be in metric. Floppy disks are tech from the US though, and everything about them is hence in inches, from physical specs to tech specs, so the metric docs translate the units.

It's like when flat screen TVs came out. When they first appeared in Europe, they sold in inch sizes. You'd go to a store in France and buy a 50 inch TV. Years later they started labeling things as "87.3cm" - and only much later started making sizes in even metric units - which are still uncommon to this day.

If you were reading a spec doc for the US 50" TV, and it was in metric, it absolutely is not something that "should be" - and is a very notable change. Just a friendly question - are you one of the scientists that worked on that mars probe that crashed?