binary code; 2-Bit-Gray-Code
<a href="//commons.wikimedia.org/w/index.php?title=User:RosarioVanTulpe&amp;action=edit&amp;redlink=1" class="new" title="User:RosarioVanTulpe (page does not exist)">RosarioVanTulpe</a>
2007-11
<span class="int-own-work" lang="en">Own work</span>