Thank's guys!
This fly isn't my concoction; it's more or less well known in some form or another, especially among few spring creek and tailwater fishemen from our fishing club... As I'm aware, they target flat flows, no matter the speed of flow. Possibility of fishing the fly on or under the surface is appreciated. Size, somewhat shape and color could be adjusted to local condition (as tie2fish mentioned PMDs).
Maybe it is off topic, but Roadkill started...
It's just my impression that CDC on nymphs and wet flies couldn't do any harm, but that it's not necessary. There are some really god feathers for that kind of (soft hackle) usage (partridge is No. 1 for me, followed by hen, jay and so many more...) But, when surface film is targeted, from both directions - CDC is great.