The Securities and Exchange Commission has approved an amendment to International Securities Exchange Rule 722, which contains definitions of complex orders. The amendment eliminates the listing of specific types of strategies that would fall within the complex order definition. A complex order is now defined as “any order involving the simultaneous purchase and/or sale of two or more different options series in the same underlying security, for the same account, in a ratio that is equal to or greater than one-to-three (.333) and less than or equal to three-to-one (3.00).” The amendment also adds a limitation on delta neutral stock-option orders.  

http://www.ise.com/assets/documents/OptionsExchange/legal/ric/2009/RIC-2009-05$Complex_Orders$20090116.pdf