Doing a bunch of slashes like this is ambiguous. But the footgun that really worries me is the international divide over whether a decimal separator should be a comma or period. 10,000.00 or 10.000,00 [1] ! Which hasn't footguned me yet, but I'm just waiting for someone to complain about a 100x unexpected financial impact of whatever they bought, because it was only supposed to be 10.00 not 10,000. Yes, I know there's an extra zero there to rescue, but still.

[1] https://en.m.wikipedia.org/wiki/Decimal_separator