Line 1 - 4 - Having created an symbol called player, and exported it for actionscript, a new instance of it is create and positioned on the stage.

Line 5 - Speed variable for the MC movement

Line 7 - 10 - Four variables are created to hold whether or not each arrow key is being pressed. For example, Up is being pressed, up will be true

Line 12 - A function to check if an arrow key is down (being pressed), using a keyboard event.

Line 13 - A swtich funciton is used to check which key is being pressed.

Line 14 - 16 - If the left key is pressed, set "left" to true and break (don't check the other keys)

Line 17 - 25 - Same as 14-16, but for the other arrow keys.

Line 27 - 28 - A default is set to break from the switch statement if anything else is pressed.

Line 32 - 50 - This function is similar to the previous one, but it checks if the arrow keys has bee in released. eg. If the left key is released, "left" is set to false.

Line 52 - So now that we have a function to find if a key has been pressed or released, we can now move the playerMc

Line 53 - 58 - If left is true deduct 5 pixels (speed) from the playerMC's current x position. If right is true, add 5 pixels to playerMc's current x position.

Line 60 - 68 - The same as above but for up & down along the y axis

Line 68 - 68 - Next we add listeners to the stage using the keyboard events (UP & DOWN), and the functions for each (keyDownCheck, keyUpCheck)

Line 69 - We also add a listener using the ENTER_FRAME and the movePlayerMc function. Using the ENTER_FRAME event will run the function at the frame rate of the movie.

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