[css3-flexbox] containing block for absolutely positioned children of a flexbox

Just wanted to be sure I'm understanding correctly: flexboxes do *not* 
act as containing blocks for absolutely-positioned children, correct? 
Instead, the flexbox's closest ancestor that is a block will serve that 
purpose. (?)

e.,g. if I have
<div id="outer">
  <div style="display:flexbox">
    <div style="position:absolute; left: 10px">test</div>
  </div>
<div>

...then my understanding is that the absolutely positioned element is 
positioned with respect to div#outer -- *not* with respect to the 
flexbox -- since div#outer is the containing block.  Is that right?

Thanks!
~Daniel