title_body: iBooks ERROR ITMS-9000 - problem with id I tried submitting my first epub to iBooks and got this error:
  
  ERROR ITMS-9000: "Shankle.epub: OEBPS/Text/introduction.xhtml(11): value of attribute "id" is invalid; must be an XML name without colons
  
  
  Here's the code from introduction.xhtml, line 11:
  
  &lt;p class="pfirst"&gt;&lt;span class="PageNumber" id="13"&gt;Page 13&lt;/span&gt; It is the purpose of this book to record the facts about the various state names. nicknames, flowers, trees, flags, birds, songs, seals, mottoes, capitol buildings, and some of the outstanding state histories.&lt;/p&gt;
  
  
  I'm confused; there are no colons in my code. It's just id="13". My epub shows no errors in Epub-Checker. Does anyone know what this error means?
upvoted_answer: An XML name must begin with a letter, underscore or colon (although in this case, the colon is prohibited).  
  
  See https://www.w3.org/TR/2000/REC-xml-20001006.html#sec-common-syn