var nINX = ( clips [ 0 ].isPrimary ) ? 1 : 0;
var oINX = ( nINX ^ 1 );

var primaryClip = clips[ oINX ];
var secondaryClip = clips[ nINX ];

secondaryClip.isPrimary = !( primaryClip.isPrimary = true )

1 = 0
0 = 1

trace ( 1^1 ) // 0
trace ( 0^1 ) // 1

function getRandomGrayscaleColor ( ) :Number
{
var brightness = Math.round (Math.random() * 255 );
return getGrayscaleColor ( brightness );
}

function getGrayscaleColor ( brightness:Number )
{
return ( brightness <<16 | brightness <<8 | brightness )
}

for ( var i = 0; i < 100; i ++ )
{
// new ball
var ball = this.attachMovie( ‘ball’, ‘ball_’ + i, this.getNextHighestDepth() );
ball._x = Stage.width * Math.random();
ball._y = Stage.width * Math.random();

// set color
var colorObj:Color = new Color ( ball );
colorObj.setRGB ( getRandomGrayscaleColor ( ) );
}

example:
// three decimal numbers, one each for R-G-B
var nRed:Number = 101;
var nGreen:Number = 153;
var nBlue:Number = 204;
cCircle.setRGB(nRed< <16 | nGreen<<8 | nBlue);

see also
http://www.flash-creations.com/notes/actionscript_operators.php