Manifest fallbacks for img and iframe

[GoogleCodeExporter]

The current manifest fallback section is not as clear as it could be that the 
method can be used for non-core media types referenced from img and iframe 
elements.

These elements should be explicitly referenced in 5.2.1 and the definition in 
5.2.2 broadened.

Original issue reported on code.google.com by mgarrish on 8 Jan 2013 at 5:14

[GoogleCodeExporter]

[deleted comment]

[GoogleCodeExporter]

[deleted comment]

[GoogleCodeExporter]

[deleted comment]

[GoogleCodeExporter]

[deleted comment]

[GoogleCodeExporter]

The following changes should be sufficient to fix this issue:

In 5.2.1, add the following new heading and requirement after "Intrinsic 
Fallback in EPUB Content Documents" to match the "Spine Resources" section:

---
Manifest Fallback in EPUB Content Documents

Foreign Resources may be referenced from img and iframe elements, and in this 
case Manifest fallbacks must be provided.
---

In 5.2.2, add the following to the end of the first paragraph:

", and for each Foreign Resource referenced from an img or iframe element in an 
XHTML Content Document."

And change the fifth paragraph to:

---
Fallback chains must conform to one of the following requirements, as 
appropriate:

- For Foreign Resources referenced from the spine, the chain must contain at 
least one EPUB Content Document.
- For Foreign Resources referenced from img and iframe elements, the chain must 
contain at least one Core Media Type Resource.

Fallback chains must not contain any circular- or self-references to items in 
the chain.
---

Original comment by mgarrish on 15 Apr 2013 at 2:56

• Changed state: ProposedSolution

[GoogleCodeExporter]

Specification has been updated:

https://code.google.com/p/epub-revision/source/detail?r=4588

Please verify and close if correct.

Original comment by mgarrish on 27 Apr 2013 at 1:27

• Changed state: FinalReview

[GoogleCodeExporter]

Original comment by [email protected] on 30 Apr 2013 at 4:28

• Changed state: Fixed

[GoogleCodeExporter]

Minor clarifications to better generalize the proposed solution:

https://code.google.com/p/epub-revision/source/detail?r=4771

Original comment by mgarrish on 16 Oct 2013 at 8:45