I'm cool with the pluto thing but I thought, there I go thinking again, that tantalum and electrolytic caps used the arc and straight line symbol and other caps used two straight line symbol. That is what has me wondering. Here we have and arc and straight line with no polarity. I can throw a 0.47 cap in and see what happens. I'm sure nothing will self destruct but I have never seen this symbol for a non-electrolytic cap before.
Yes, I've seen that convention too, not sure it was recently though. There are regional differences as well.