I’m currently researching the design of elevator button symbols—the door open and close symbols, to be precise—and my search for reference material and real-world usage has taken me to some pretty bizarre places.
My initial finds were not at all surprising; I found countless articles and blog posting, each with many to dozens of comments that all echoed the same thought—everybody has trouble finding the door open button in an elevator, and most have difficulty telling the open and close buttons apart from each other.
Another search led me to the standard symbols for clothing care (where an article discussed the change of the “don’t bleach” symbol from a filled triangle to an open one).
My most recent searches led me to forum discussions questioning what the pac-man symbol on the battery door of a camera was, while another link in that same search revealed the source and meaning of the symbol (that the lens cap must be open before this operation is performed), the fact that symbols for cameras have been defined by at least two different organizations, one of which has no business designing symbols and is as likely to cause injury as confusion with their misunderstanding of core symbol design concepts. (Hint: never misappropriate a symbol designed for safety for an unrelated purpose.)
I am already shaking my head in anticipation of what I will find when I continue my symbol searching.