The term "Separation Date" is unfamiliar to me, so I looked for a definition. Which of the three sub-definitions being used by Spider is unclear to me at this time.

Snug

"The Separation Time is the Close of Business on the eighth Business Day after the earliest of (i) the “Stock Acquisition Date”, which is generally the first date of public announcement of facts indicating that a Person has become an Acquiring Person; (ii) the date of the commencement of, or first public announcement of the intent of any Person (other than the Company or any Affiliate of the Company) to commence a Take-over Bid (other than a Permitted Bid or a Competing Permitted Bid, and the Rights Plan requires such bid to continue to satisfy the requirements of a Permitted Bid or Competing Permitted Bid); and (iii) the date at which a Permitted Bid ceases to be a Permitted Bid. In either case, the Separation Time can be such later date as may from time to time be determined by the Board of Directors. If a Take-over Bid expires, is cancelled, terminated or otherwise withdrawn prior to the Separation Time, it shall be deemed never to have been made."

http://www.wikinvest.com/stock/GSI_Group_(GSIG)/Summary_Shareholder_Rights_Plan