In this context, they mention specifically that they are call options so it may mean something different. A strip can refer to multiple options that cannot be sold separately. E.g.
You have 4 call options. One matures in June 07, one in September 07, one in December 07 and one in March 08. You can use the term strip to say that you cannot buy, or sell these options individually, but must buy them altogether.
Here is an article including the definition:
http://www.cbot.com/cbot/pub/page/0,3181,1993,00.html