Nature gives the rule

Without that I've read the whole Compendium, not even the rich entries for the various editions of the Bibliotheque Oulipienne, I begin to think that the subtlest Oulipian restriction is that known as "Canada Dry":

The name of this procedure is taken from the soft drink marketed as "the champagne of ginger ales". The drink may have bubbles, but it isn't champagne; in the words of Paul Fournel, who coined the term, a Canada Dry text "has the taste and colour of a restriction but does not follow a restriction".

Not a determinate restriction, anyway (or rather, not one visible from the resulting text), but it clearly is a restriction: appear to follow a determinate rule, but actually follow none (other than this very rule).  As GC Lichtenberg would say, this is a Kantian idea (except not really really).  Examples:

Wand-escape ether evil draws.

"Crack legions apprehend undue assaults," said conductor of lead tank, staccato.

Franz of black fiacre aspires to Luke's matches.

Comments

[Matt Weiner]

To tell a long involved story that ends with an oddly stilted sentence that sounds like a pun, but is not, would be a Canada Dry pseudo-shaggy dog story, then, would it not? In case anyone had ever done or suggested such a thing.

[ben wolfson]

That is a good idea, Weiner, who knows that he has suggested just such a thing, but is "shaggy dog story pun" really a restriction in the proper way?