For 3.5 inch disks you can tell for if it is a 1.44Mb disk or not by the tell tale hole on the side opposite the write protect slider. If it's got the hole it is high capacity, i.e. 1.44Mb, if not it is one of the lower capacities. See number 1 here - Floppy disk - Wikipedia[^]

It was never a decimal point in the days of shillings, it was a separator the same as in software versions. Obvious when you think it through, definition of decimal is "relating to or denoting a system of numbers and arithmetic based on the number ten, tenth parts, and powers of ten", there were 20 shillings in a pound and 12 pence in a shilling so no multiples of ten. And even in the days of shillings the full stop was rarely used in writing down currency (at least in my experience), for instance two pounds, five shillings and six pence would normally be written "£2 5/6"