[GeoffR]

So it sounds like my SVG code only works on Kobo and Calibre, and the orientation code only works on Kobo.

Anyone have any suggestions how to achieve the effect on other devices?

Edit: Here is one thing I tried using this simpler SVG, but it has the unacceptable flaw that some of the map is lost if the image aspect is too wide to fit on two pages. I can think of a way to fix it up on Adobe RMSDK readers using the page-aspect() conditional, but there doesn't seem to be an equivalent @media query to get the page aspect?.

(This works the same on Kobo's ACCESS and RMSDK10 readers and the Calibre viewer. Not tested on others.)

  <div style="margin:0;max-height:100%;max-width:100%;overflow:hidden;">
    <svg:svg viewBox="0 0 600 400" width="100%" height="100%"
	     preserveAspectRatio="xMinYMid slice">
	<svg:image height="400" width="600" xlink:href="map.png"/>
    </svg:svg>
  </div>

  <div style="margin:0;max-height:100%;max-width:100%;overflow:hidden;">
    <svg:svg viewBox="0 0 600 400" width="100%" height="100%"
	     preserveAspectRatio="xMaxYMid slice">
      <svg:image height="400" width="600" xlink:href="map.png"/>
    </svg:svg>
  </div>