Certain names imply specific symbols being used. For example, Binary Puzzles use 1s and 0s (i.e. binary numbers), Tic-Tac-Logic uses Xs and Os (like tic-tac-toe), Eins und Zwei uses 1s and 2s, and Tohu-Wa-Vohu uses T and V symbols. However, many of the names are used for any variation of symbols. Black and white circles (or squares) are another commonly used pair of symbols. Any variation of two numbers, letters, colors, or pictures can work as the two symbols, though it is generally common for the symbols to be 1s, Xs, or shapes.