Add context to <assert>

[leo-barnes]

We have a case where we have the same SHALL statements that we would like to have <assert> around, but in multiple sections. Currently these generate the same assert ID, but we would ideally want to be able to add a context to the assert so that we get a different ID for each section.

What's the best way of doing this? Can we add some kind of hidden context to the text that does not show up?

AOMediaCodec/av1-avif#299

[leo-barnes]

We have this:

<h3 id="baseline-profile"><dfn export>AVIF Baseline Profile</dfn></h3>
...
The following shared conditions and requirements from [[!MIAF]] should apply:
    - <assert>[=grid-limit=] (subclause 8.4)</assert>
    - <assert>[=single-track=] (subclause 8.5)</assert>
    - <assert>[=edit-lists=] (subclause 8.6)</assert>
...
<h3 id="advanced-profile"><dfn export>AVIF Advanced Profile</dfn></h3>
...
The following shared conditions and requirements from [[!MIAF]] should apply:
    - <assert>[=grid-limit=] (subclause 8.4)</assert>
    - <assert>[=single-track=] (subclause 8.5)</assert>
    - <assert>[=edit-lists=] (subclause 8.6)</assert>

It would be great if we could do something like <assert for="baseline-profile"> and <assert for="advanced-profile">

[tabatkins]

Yeah, a for attribute (and an assert-for you can put on an ancestor, which'll carry down into any asserts) that gets included in the hash generation seems like the most straightforward way to handle this.