A crosswalk signal showing the symbol for "walk". Walking signal symbol is from Manual on Uniform Traffic Control Devices (MUTCD), Millennium Edition with incorporated Revision Number 1 changes, dated December 28, 2001; "Any traffic control device design or application provision contained in this Manual shall be considered to be in the public domain. Traffic control devices contained in this Manual shall not be protected by a patent or copyright, except for the Interstate Shield."; http://mutcd.fhwa.dot.gov/HTM/millennium/12.28.01/introduction/MUTCD_intro.htm