title: Name of nearest ancestor element that is position relative/absolute and provides absolute coords
body: <p>I spent a while researching which SE site to post this on, but none seemed more appropriate than SO.</p>
  
  <p>I'm trying to document something regarding coordinate systems in HTML, and am keen not to invent a new term if one already exists.</p>
  
  <p>With regards to absolute positioning:</p>
  
  <blockquote>
    <p><a href="https://stackoverflow.com/a/105035/14357">By default, the container is the browser window, but if a parent element either has position: relative or position: absolute set on it, then it will act as the parent for positioning coordinates for its children.</a></p>
  </blockquote>
  
  <p>Does this "positioning parent" have a snappier, official(ish) name?</p>