Hi Josh, Thanks for the response. Let me try to outline what I'm doing a bit better here. I am attempting to use the common section once in each book. Inside of this section, there are sub-sections which have IDs that are referenced a few places in each book. Mostly in the sense that I say "Please refer to *here* for more detailed information" where here is a link to one of the IDs. And some code... <book id="Book_A"> ... <xi:include href="../common/Introduction.xml" /> <xi:include href="some_chapter_which_hrefs_intro.xml" /> ... </book> <book id="Book_B"> ... <xi:include href="../common/Introduction.xml" /> <xi:include href="some_chapter_which_hrefs_intro.xml" /> ... </book> For this example it may be possible to re-write the Introduction to better suit my needs and avoid this, but I will come across the same issue with another piece of shared code shortly and figured I may as well tackle the issue from the beginning. The errors I get when running publican have to do with being unable to load Introduction.xml because the IDs are already in use by the time the second book attempts to use it. Thanks again. -- Kendall <div class="gmail_quote">On Wed, Aug 1, 2012 at 4:39 AM, Joshua J Wulf <<a href="mailto:jwulf@redhat.com" target="_blank">jwulf@redhat.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <div bgcolor="#FFFFFF" text="#000000"><div><div class="h5"> <div>On 08/01/2012 08:37 AM, Kendall Moore wrote: </div> <blockquote type="cite">Hello Publican users, I'm currently stuck trying to do something I would have guessed to be a simple task. I have a set of two books, and some of the content for them I would like to be shared between the books. I created a directory for the common content (at the same level as the directories for the two books) and put the XML files which contain sections in it. Now, when I try to use an xi:include to grab these sections in each of the books, I get an error trying to run publican with the '--formats=test' option. The issue seems to be that some of the tags inside of these common files have IDs, and each book attempts to import the IDs into its own namespace but fails to do so because the IDs aren't unique. Specifically, the error(s) look like the following: ../common/<some_xml_file>:6: validity error : ID <some_id> already defined If I remove all of the IDs from these common files then there is no issue, but unfortunately that is not an option for me. I link to the pieces with IDs other places by way of xrefs and need an ID to do so (or at least that's my understanding). Any help on the subject is greatly appreciated! -- Kendall <fieldset></fieldset> </blockquote> </div></div> Hi Kendall, yes you need an ID to be the target for an xref. You didn't state it, but are you including your common content more than once in the same book? If you give some more specifics about your use case (maybe even some sample code) I can give some suggestions - I've worked around this issue several times with different strategies. - Josh </div> </blockquote></div>