Originally Posted by Toxaris
I recommend looking at the site from Jedisaber. He explains the ePUB2 format quite well and it will help you.
I already found Jedisabers site. And the funny thing is: I copied his content.opf ... with the 2 question marks
but yeah, his site is really helpful.
As I said, the "version error" was gone, once I changed the path in the content.opf file. After that I got some other errors, but mostly they were caused by bad bracketing (a closing tag too much) and stuff like that.
The only error I still get is about a jpg file. ("not conform to the opf standard"). I guess I will take the same html and jpg files and run them through Calibre and compare the outcoming code with my own code. If that doesn't help me then I will post it here.
But again, thanks for your helpful input.
Edit: never mind what I said earlier, about the jpg file. It seems as if I found the error. I used
After changing the "jpg" to "jpeg", the image seems to be fine according to epub checker.