This excerpt taken from the VTAL DEF 14A filed Apr 22, 2008.
Offering Periods and Purchase Rights
Shares of common stock are offered under the ESPP through a series of offering periods of three months in duration. Each offering period runs for a calendar quarter, with a purchase date on the last date of that offering period.
When an eligible employee elects to join an offering period, he or she is granted a purchase right to acquire shares of common stock on a purchase date within the offering period. On the purchase date, all payroll deductions collected from the participant are automatically applied to the purchase of common stock, subject to certain limitations.
The most recent offering period began on April 1, 2008 and is scheduled to end on the last business day in June 2008. The next offering period will begin on July 1, 2008 and run through the last business day in September 2008, regardless of whether the shareholders approve the share increase that is part of this proposal. If the shareholders do not approve the share increase, we will likely not be able to offer employees the right to purchase shares under the ESPP on the September 2008 purchase date because we may not have a sufficient number of shares reserved to meet demand.