[css-regions]

In section 3.2.1 of CSS Regions [1], it says you can't have a element create a flow and also consume the same flow, and it gives this example:
> #id { flow-into: foolish; flow-from: foolish; }
> would move the #id element to a "foolish" named flow, and try to make the #id element a CSS Region for the "foolish" named flow. The "foolish" named flow would then contain its own region, creating a cycle. So the #id element does not become a CSS Region.
> 

However, I think that restriction should only be the case when the keyword "contents" is not in the 'flow-from'. It doesn't say that anywhere that I could find, but it would be useful to do something like this:

> #id { flow-into: significant  content; flow-from:significant;
> }
> .some-empty-things {flow-from:significant;}

That way, the element matching #id could have a large amount of content in the natural markup, but it's height could be limited so that it flowed through the original container AND the additional regions. There would be no problem with a cycle to break. 

Brad Kemper

1) http://www.w3.org/TR/css3-regions/#circular-dependencies