有关paypal创建按钮的值

 <form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post">
  <input type="hidden" name="cmd" value="_s-xclick">
  <input type="hidden" name="hosted_button_id" value="6RNT8A4HBBJRE">
  <input type="image"
    src="https://www.sandbox.paypal.com/en_US/i/btn/btn_buynowCC_LG.gif"
    name="submit" alt="PayPal - The safer, easier way to pay online!">
  <img alt="" src="https://www.sandbox.paypal.com/en_US/i/scr/pixel.gif"
    width="1" height="1">
</form>

不知道其中的hosted_button_id的控件的值是怎么获取到的

http://wenku.baidu.com/link?url=5xv4OIpiVeZAMACROo0quQIkR98BAL6q49ic_bDx7qbS0HKKBAojouidSo-9ikctAYXw6khcd4wMevr1g35FF2EM22ThaH2VJaFRLVbzZzS