I got this term from LukeHohmann's book JourneyOftheSoftwareProfessional.  He devotes Sec 3.2 to it.  In his words:

Instead of using the simple future tense and asking
	 :	What ''should'' the system do?

we should use the future perfect tense and ask
	 :	What ''will'' the system have done?

Why? By changing the tense of the verb, we change the way we think about the future ... descriptions generated by ... subjects using future perfect thinking were significantly more detailed than those who engaged in mere future thinking ... By helping to create detail, it helps us solve thorny problems ''as early as possible'' in the development of [a] system. pp. 48-49.

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Wow! In really simple terms this explains something I have been trying to get across to other developers for years. Seeing it in print, I suddenly realize that this is what all the "tracing" I was forced to do in my first computer class really taught me (way back when my age was barely out of the single digits). Much better than ReadItLikeaComputer.  -- JeffShelby
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Interesting insight. Another one along these lines is from ExploringRequirements by Gause & Weinberg. Phrase questions and requirements in terms of verbs, not nouns. "Design me a chair" is way less useful than "Design me something to sit on comfortably." I'm not doing a good job explaining this, but when the operative word is a noun, people tend to get bogged down in semantic questions and explore few alternatives.  Roughly the same idea expressed with a verb leads people to explore different ideas, different questions, and never consider opening a dictionary to resolve an argument. -- BenKovitz