This excerpt taken from the IWOV DEF 14A filed Apr 29, 2008.
Amendment and Termination of the Plan
The Board of Directors may, at any time or from time to time, amend or terminate the ESPP, except that such termination shall not affect options previously granted nor, generally, may any amendment make any change in an option previously granted that adversely affects the rights of any participant. To the extent necessary to comply with Section 423 of the Code, we shall obtain stockholder approval in such a manner and to such a degree as required.
If the extension of the ESPPs term is approved, the ESPP will continue until the earlier of termination by our Board of Directors, issuance of all of the shares reserved for issuance under the ESPP or April 17, 2018.