text: Upon the initial public offering of the Company on March 6, 1997, all milestone awards and milestone options granted under the milestone 
  a rrangement (with the exception of 49,819 options to certain key employees which vested equally over the two years following the initial 
  public offering) vested and all shares became immediately issuable to beneficiaries of milestone awards and options. At that time, 800,520 
  milestone awards and 232,078 milestone options were exercised. As of December 31, 2000 1,428,303 milestone options remain unexercised. 