Referencing the same equation multiple times.

[MartheGjelstad]

Often an equation is referenced mutliple times, so the same id is referenced multiple times. It seems like if the attribute role="doc-backlink" is used, the equation can only be referenced one time.

This is the error from Webarch: "The backlink with the href "#equation-001" attribute must resolve to exactly one noteref in the publication"

[MartheGjelstad]

I now believe the issue is that the equation (with an id) doesn't have any note reference to another element. So you can only navigate from where the equation is referenced back to the equation, but not from the equation back to the text where it was referenced. Is it possible to create such a back-and-forth link if the equation is referenced multiple times?

[samimaattaCelia]

Usually in (good) reading systems you would also have a shortcut to move back to the previous location when you jump to other sections in an ebook. This could also be a solution to this, but still the problem remains that it the back-and-forth would have to be one-to-one when going back to the location you just were in.

[MartheGjelstad]

Look into how the "doc-backlink" works.

https://daisy.github.io/reading-apps-ux-reqs/requirements/published/FINAL-20251031/

[MartheGjelstad]

I asked about this issue in the Daisy math mailing list.

My question was: "Often an equation has a label, such as "Equation 1". Later, this equation is referenced, for example "as we can see from Equation 1...". It would be useful to be able to jump to the equation and then return to the location in the text. Should this be done by using anchor tags and the ARIA role doc-backlink. Also, often an equation is referenced multiple times. How could this be solved?"

I got the following answer (my summary):

• Properly identified links is the best way to handle equation callouts.
• When an equation is referenced multiple times, the backlink is a problem.
• One solution is to always return to the first place where the equation was referenced. This is a short-term solution until all eBook readers offer a return button, so the backlink is no longer necessary.

[samimaattaCelia]

Here is some documentation about doc-backlink: doc-backlink - Accessible Publishing Knowledge Base

[MartheGjelstad]

We need to investigate this further to make any decisions.

A comment about the example in the guidelines: Tabindex should only be used for interactive elements. Should therefore be removed from markup of labeling an equation.

[samimaattaCelia]

I read the doc-backlink: doc-backlink - Accessible Publishing Knowledge Base description and to my understanding it doesn't limit backlinking to only one reference. I asked my coworker for an opinion as well.

I think this might be a mistake in WebArch unless they have another source for this validation rule.

Bug in Thorium with screen readers?

I also tested moving back from the linked location in Thorium and you can use the shortcut Shift + Backspace (or you can change it in the settings) to move back to the link's location. I did however notice that using NVDA and the shortcut jumps to the start of the file and then to the linked location after using the shortcut twice. It can be confusing to the user. It doesn't seem that the reason is a mixed shortcut with NVDA, because there isn't a same combination of keys for this.

If somebody else can verify this, please let me know, so I can report it as a bug to Thorium Github.

[TimArborealis]

I think it would be good to include Linda and Elise in this discussion.

[lindheli]

To me "backlink" means "take me back to where I came from". If that is the correct interpretation, I guess it is not possible to use a backlink that takes you somewhere else, like the first occurrence of the reference. That would be very confusing.
Could perhaps just an ordinary link to the equation be an accepted solution, and then use the Go back in navigation history in the reader?

[MartheGjelstad]

Change the example to what's working now. And use normal "href". No backlink.