[css3-break] What is a Class 3 unforced break?

Hello everybody,
The CSS Fragmentation spec defines three classes of possible break points. The third one[1] is defined as "Between the content edge of a block container box and the outer edges of its child content (margin edges of block-level children or line box edges for inline-level children) if there is a (non-zero) gap between them."

The only scenario I can think of that matches this description is that of a block that has 'height' or 'min-height' specified while the computed height of its children is smaller than this specified 'height'/'min-height'.
Is this correct? Am I missing any other scenario that pertains to this class of break points?

Thanks in advance,
Mihai


[1] http://dev.w3.org/csswg/css3-break/#end-block