Originally Posted by Chang
My conclusion is that ADE and iBooks (webkit) reading systems are unable to read external SVG style sheets.
I guess you are right.
Maybe chapter 2.5 at http://idpf.org/epub/20/spec/OPS_2.0.1_draft.htm
" class="wikilink" title="MR Wiki entry">http://idpf.org/epub/20/spec/OPS_2.0.1_draft.htm
are useful for you. There you'll find something about SVG within epub standard.
Are the devices you mentioned (ADE and iBooks) "SVG-ready"? There should be something written in the manual...