Re: [csswg-drafts] [css-content] Need to clarify in-flow presentation implications for bookmarks

In subsequent discussion with Tony Graham of Antenna House I realized that I had misunderstood the intent of the CSS bookmark feature, in that it is intended to be used as properties on the element being bookmarked, not as a way to generate a separate navigation structure that then links to the elements being bookmarked (which is how XSL-FO works and how Antenna House's CSS extensions allow you to create bookmarks).

So in the context of that understanding my comments are either non-sensical (in that if something was hidden you probably wouldn't want a bookmark for it.

The use cases the I have that drove this analysis cannot be addressed by this "bookmark as decoration of thing bookmarked" approach because in my case it will often be the case that the hierarchy of the HTML structure (e.g., sections) will not match the desired bookmark structure in one or more ways.

For example, sections that are peers may need to be reflected as a hierarchy or there may be levels in the hierarchy that need to be reflected in the bookmarks but that are not explicit in the source.

Another use case for bookmarks is including a generated back-of-the-book index (that is, something that would never reflect the actual order and hierarchy of the source) in the bookmark tree. This cannot be done through decoration alone.

So without a defined way to generate an arbitrary navigation structure that becomes bookmarks with links to the actual target source (as opposed to the elements that define the navigation structure itself) there is a whole host of bookmark use cases that CSS as currently defined cannot support.

I think this can be stated as there needs to be away to have HTML5-style navigation structures with links to the things being navigated to (for example, as used by the EPUB 3 standard) to generate PDF bookmarks.

In that case, the navigation structure may or may not also be rendered in the main flow (but usually it would not be). Here I have basically two use cases:

1. Given an in-flow table of contents have it serve also as the definition fo the PDF bookmarks
2. Use a completely separate navigation structure in the HTML that is *not* shown in-flow and produces the PDF bookmarks.

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Received on Thursday, 1 November 2018 19:47:20 UTC