One minor nit. There are 5 named entities allowed in epub3, & amp;, & lt;, & gt;, & apos; and & quot;.
I also ran into one epub3 where the author decided to add a mass of entities using:
Code:
<!DOCTYPE html [
<!ENTITY nbsp "& #160;">
<!ENTITY Aacute "& #193;">
<!ENTITY bull "& #8226;">
<!ENTITY ldquo "& #8220;">
<!ENTITY rdquo "& #8221;">
<!ENTITY pound "& #163;">
<!ENTITY iquest "& #191;">
.... for about 20 more entries.
]>