French term (edited): Les documents chpeau

It might be "key documents", but it could be argued that the devil is in the detail, or in the four crématoire or somewhere, and that a document way down the hierarchy of documents is actually more important than any of the general documents at the top (or bottom, depending how you look at it) of the arborescence.

Thus, the helmet of the little corporal manning a gun and fending off repeated attacks by frenzied infantrymen (enemy infantrymen, I mean) while continuing to shell enemy positions until the battle is won - and indeed the little corporal himself -, though a mere detail, might actually be more important in the general (or corporal) scheme of things than the cap of the general - indeed, the general himself - who planned the attack but actually got it all horribly wrong, as has been their wont.

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Note added at 3 hrs (2011-04-22 13:11:06 GMT)
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@Bashiqa - Blowing a raspberry is often advisable in such situations. I shall consider my raspberry blown.