[slowsmile]

@AlanHK...I'm not sure if this is what you're looking for but I've been working on a new plugin that properly checks, reports and, if possible, fixes id attributes and book id errors in the epub. It does the following:

* Checks all id attributes in the xhtml files, opf and ncx.
* Automatically fixes simple problems like illegal spaces or illegal first char digit errors.
* Replaces any bad book ids with correct book ids in the toc.ncx and content.opf.
* Reports all id errors with an accurate reason.
* Reports if the id error has been fixed or not.

Please be aware that I'm testing this plugin right now which still has one strange bug -- if there is an error in the toc.ncx only, the error line number reporting may be inaccurate the first time you run the plugin on an epub. But if you run the plugin a second time, the line numbering will usually be correct. I haven't released this plugin on MR yet because of this bug. Also, if you do use the plugin below, some feedback would be greatly appreciated.

Please read the README.html file in the in the zip file or plugin dir for more details.