Would it be useful to allow and enable more than one `<extent units="...">` per layer

[prushforth]

One advantage might be that you could put several different projections in a single layer / mapml file and the client could pick the one that suits the map at the time.

Another possibility is that it could provide a scope for link templates and template variable names, which might help decrease error rates when editing them by hand / copying pasting+modifying (a standard coding method!).

Idea / question for discussion, pros and cons and so on.

[prushforth]

Maybe the layer control could designate one summary/details per <extent>, so that you could turn on/off, and control the opacity of contents. Just a thought, there might be complications.

[ahmadayubi]

I think the suggestion to have a separate summary for the different <link ref=",,,"> elements was made in the past too.

[prushforth]

We should have a way to label an extent, which is clear for authors and implementers.

I suggest adding a label attribute to the extent element. If absent, the value would be inherited from the parent layer.

[Malvoz]

suggest adding a label attribute to the extent element.

Sounds reasonable.

If absent, the value would be inherited from the parent layer.

Not being able to differentiate between them seems problematic, there's a related issue in terms of what to do when a name/label hasn't been provided: #319.

[prushforth]

@Malvoz a multiple-extent layer could provide access to the individual extents' settings via the settings button you proposed. Each child extent could be considered an individual "setting" of the parent, each with its own settings button that exposes the same settings structure below / inside it, (except there would be no more levels of settings - settings buttons, that is) , just the settings controls themselves i.e. opacity slider, check input, remove button, etc. (those could each be inside a details/summary, as you've shown). WDYT?

cc @Anshpreet8

[Malvoz]

Yes I think that'd form a logical structure.

those could each be inside a details/summary, as you've shown

I only kept details because that's what's currently used, I'm not completely sold on the idea that each setting (opacity/style/time) should in fact be wrapped in a details element.