vg: According to the Form 4, the options exercised were granted under the 1995 plan. Based on the normal 10 year period for exercising the options, the expiration date in May of this year would also indicate that they were granted in 1995. I think the 1997 date you may be referring to is when some of the options became vested. From the Form-4
"2. A grant of options which vested in full as follows: 8,333 on 06/30/1995, and 41,667 on 12/31/1997.
3. Granted pursuant to the InterDigital Communications Corporation 1995 Stock Option Plan for Employees and Outside Directors."
Seems like the options that HG exercised today are from around 1997..