Identifying resources

[qnga]

1.1.1. Source
The target resource MUST be identified by a URL relative to the root of its parent publication.
If the annotation is attached to an EPUB, the source value must also be present as one of the item/@href values of the manifest element.
If the annotation is attached to a Web Publication, the source value must also be present as one of the readingOrder/@href or resource/@href values on the Web Publication Manifest.

If I understand correctly, there might be an issue there. One is required to use a URL relative to the root and the resource href. Unfortunately, hrefs can be absolute URLs in RWPM. Resources with absolute hrefs could not be annotated.

If we target only EPUB and RWPM, using the href whatever it is seems just fine.