Epubcheck fails to validate ID CS 5 date value

Question

Hello,
I applied for an appication with Apple to distribute my ebook via their iBookstore. In Apple's specifications it says my epub file "Must" past epubcheck 1.0.5. I downloaded epubcheck and ran the code in Terminal. There was a minor hyperlink error, which I've fixed, however, I can not get rid of the following error.
epubcheck 1.0.5
ERROR: /Users/Digital/Desktop/XXXX-eBook.epub/OEBPS/content.opf(2): date value '' is not valid, YYYY[-MM[-DD]] expected
Thinking that it could be an epubcheck program error I downoaded the newer version...
epubcheck 1.1
ERROR: /Users/Digital/Desktop/XXXX-eBook.epub/OEBPS/content.opf(2): date value '' is not valid. The date must be in the form YYYY, YYYY-MM or YYYY-MM-DD (e.g., "1993", "1993-05", or "1993-05-01"). See http://www.w3.org/TR/NOTE-datetime.
I've done some research and found this fix:
Troubleshooting the epub’s ‘date’ metadata
(http://ebw.co/kbase/creating-epub-from-indesign/after-indesign-export-to-epub/add-metadata)
If you check your epub with epubcheck version 1.0.5 or later, you may get this error message:
ERROR: title.epub/OEBPS/content.opf(2): date value '' is not valid, YYYY[-MM[-DD]] expected
To fix the date: in the metadata section of your content.opf file, replace this code
<dc:date/>
with this
<dc:date>2010-06</dc:date>
That date’s an example, of course. Change that to your publication  date. (If you don’t have a <dc:date/> tag, just add the line.)
So now the question - why does ID CS 5 not output the date properly, and how do I open the opf file to insert the corrected code? Or is there another way - or have I failed to insert a date somewhere in my ID file. If so...where do I do that?
Thanks.

Answer 1

Ok, I got it fixed. I found this article: http://www.webvivant.com/fixing-InDesign-epub-2.html
"...As content.opf is just a plain text file, you can open it with your  favourite text editor. Make sure you use a text editor and not a word  processor - you want something that can save ordinary text files."
I opened the content.opf file in TextEdit and found the <dc:date/> empty as epubchecker suggested. I replaced it with this: <dc:date>2011-03</dc:date>
I opened my eBook file with Springy (http://www.springyarchiver.com) and replaced old content.opf with the newly saved file. Ran epubcheck again in Terminal and got these results.
No errors or warnings detected
Hope this helps someone in the future...