MACROMEDIA FLASH MX 2004-ACTIONSCRIPT LANGUAGE Reference page 75

If you trace the following example, you see that the bits have been pushed two spaces to the left:
// 2 binary == 0010
// 8 binary == 1000
trace(2 << 2); // output: 8
See also
>>= (bitwise right shift and assignment), >> (bitwise right shift), <<= (bitwise left shift and
assignment), >>> (bitwise unsigned right shift), >>>= (bitwise unsigned right shift and
assignment)
<< (bitwise left shift) 75