Reordered & relisted requirements to match prose

[BigBlueHat]

• resorted and reworded Recommended Descriptive Properties
• moved Reading Progression up to Recommended Descriptive Properties
• moved Resource List into Recommended Structural Properties

All changes made to these list match currently merged prose text
about the same requirements.

Related (in part) to conversations in #198. Depending on which area of the spec you were referring to the "resource list" was either required or recommended. This PR makes the list match the prose--i.e. fixes that bug in the requirements list.

---

Preview | Diff

[BigBlueHat]

Default Reading Order is actually not currently required according to the prose ("If a user agent requires a default reading order..."). Consequently, I'm adding a separate commit to move "Default Reading Order" down to Recommended to match the prose.

[mattgarrish]

is actually not currently required according to the prose

That prose was inserted for error handling. The "if" is not making the reading order non-required, but acknowledging that a user agent might do something else if there isn't a default reading order (disable sequential navigation, bail out on the publication, ...).

Goes back to the discussions we had about whether its enough to say properties are required without also saying what should happen when they are omitted.

I agree it's confusing, but I'm not a big fan of making user agents construct things the author forgot (at least not with the latitude given). If we want consistency, the answer here is probably that the user agent disable any progression features when a default reading order isn't specified.

[HadrienGardeur]

@mattgarrish I would suggest a slightly different solution: if the author forgot to include a default reading order, the UA defaults to a default reading order where the WP address is the only item listed.

Right now, the WP address and the default reading order are the only two requirements that we have.

[mattgarrish]

@HadrienGardeur Sure, any approach that is going to be consistent across user agents is fine with me. I understand the desire to have user agents fill in the blanks, but we should try much harder to ensure that the experience is consistent.

Titles are another case, where depending on the user agent you use you might discover the same publication has different names if one isn't specified in the infoset.

[BigBlueHat]

we should try much harder to ensure that the experience is consistent.

Completely agree with this statement. There are a lot of assumed experiences which we've not (yet?) said even exist. For instance...

if there isn't a default reading order (disable sequential navigation, bail out on the publication, ...).

Those expectations seem related to how EPUB's are experienced now. If we want to inherit those (or recreate them on the Web), we need state them and then map them into what properties (descriptive or structural) afford those experiences.

It would clear up a lot of confusion in discussions, me thinks. 😄

[BigBlueHat]

Also, I'll remove that last commit about Reading Order shortly, and once done, I believe we'll be good to go on this PR, correct?

[iherman]

@mattgarrish merge this, too (before the F2F)?

[mattgarrish]

I believe @BigBlueHat still has to make an update before we merge.

[iherman]

@BigBlueHat there is now a conflict with the main branch (I guess due to the merged PR of @HadrienGardeur), and I would expect some conflicts with the other PR I have just filed (#211). I wonder whether it is not quicker if you looked at #211 and possibly made some changes/commits on that one, rather than chasing the conflicts in this PR (which has become outdated...)

[iherman]

B.t.w., the F2F resolution is analogous to #200 (comment) of @HadrienGardeur, and is part of #211 .

[iherman]

Created #231 separately to handle conflicts, and merged that one.