2. Validated backlog: items from the opportunity backlog which have been examined, researched and discussed enough to be considered valid candidates for future development.

• Opportunity backlog contains big items with little breakdown, Epics. These may be happen sometime in the longer term, over future quarters and years. They may appear on a roadmap or they may be more speculative.
• Validated backlog items should be at the story size - small enough to be deliverable soon but demonstrating real business value. These items may be developed sometime in the next quarter so they appear on the quarterly plan.
• Iteration backlog items are here and now, they are task sized and are in the current iteration.

There is no point in doing more work on any item until it moves to the next backlog, into the next planning horizon. At each stage some items will disappear, upon closer examination they will not be judged worthwhile. 

• Items in the Iteration backlog may well have detailed effort estimates arrived at from work breakdown if needed
• Items in the Validated backlog probably have ballpark estimates and, very importantly, value estimates (how much is this item worth?)
• Items in the Opportunity backlog might have effort scores taken from historical averages (why spend time estimating something that might not happen?) and can only move to the Validated backlog when a value estimate has been made and the item has been judged as worth doing relative to everything else

Three backlogs. What do you think? Good idea or silly?