The pictograms printed on distribution packaging to tell a handler how to treat it. ISO 780 defines them, which makes this one of the few everyday systems with a real definer — and the standard is paywalled and was not read, so it is cited for scope while the individual meanings come from reference works. The most reproduced member is also the least respected: two upward arrows appear on a great many boxes whose contents have no orientation requirement at all.
Two upward arrows beside a package outline, fixing its orientation.
A broken wine glass warning that contents are breakable.
An umbrella under rain, requiring the package be kept from wet.
A thermometer between two bounds, giving a storage temperature range.
A crossed-out box on a box, forbidding anything placed on top.
A sun beside a package, requiring storage out of direct light.
A cross in a circle marking where a package balances.