The ISO 9000 family of graphical symbols (approved over the course of the past decade) are what you see on most U.S. planes everyday. These upside-down exclamation points keep you safe.

NEMA Publishes Standard for Graphic Symbols for Arc Welding, Cutting Apparatus Mar 11, 2009 The National Electrical Manufacturers Association (NEMA) has published EW 4-2009, the first new edition ...

Professional societies such as Scientific Apparatus Makers Association (SAMA), ISA, and ISO provided guidelines as to industry usage of functional diagrams. The popular but older standards: PMC ...