On a sheet of paper, draw a "reasonably short closed doodle." Your line must not pass through an intersection you have already drawn, and the crossings must be "genuine," with distinct tangents. Throughout the rest of this article, such drawings will be referred to as "curves."
One Gauss code for this doodle is (1, 2, 3, 4, 5, 6, 2, 1, 6, 5, 4, 3).
Now choose a starting point between two crossings and a direction of travel, then number the crossings successively 1, 2, 3…, skipping any that have already been numbered. To obtain the doodle's Gauss code, follow the curve again and record the numbers in the order in which you encounter them. You should obtain a sequence of 2n numbers between 1 and n, each appearing twice, where n is the number of crossings.
