Why would this be accepted: (the link works)
<a href="Prologue.xhtml">

But this is not: (the link doesn't work)
<a href="c01.xhtml">

And must be changed to:
<a href="OEBPS/Text/c01.xhtml">

Even though both "Prologue.xhtml" and "c01.xhtml" are in the text folder with the "TOC.xhtml" file that includes the <a href call.