[docbook] equations [was: formal objects in docbook 5]

[Doug du Boulay <ddb at owari dot msl dot titech dot ac dot jp>]

Norman Walsh <ndw@nwalsh.com> wrote:
> / Stefan Seefeld <seefeld@sympatico.ca> was heard to say:
> | docbook uses the term 'formal object' (or short 'formal') in a number
> | of places to demark some elements. I couldn't find any clear 
definition
> | of what it means for an element to be 'formal', other than that it has
> | a title.
> 
> That's all it means.
> 
> | I then ran the first question of 'Some Open Questions' in
> http://norman.walsh.name/2003/05/21/docbook:
> |
> | "Is the distinction between formal/informal useful anymore?"
> |
> | What is the answer to this question in the context of the upcoming
> | docbook 5 schema ?
> 
> DocBook NG still has both the formal and informal versions.
> 
> The odd man out in all this is equation which, for backwards
> compatibility reasons in DocBook *4* still has an *optional* title,
> even though there's also an informalequation element. I see two
> possible ways forward:
> 
>   1. Keep the formal/informal distinction and make title on equation
>      required. (This is what I've actually done in DocBook NG.)
> 
>   2. Drop the distinction, drop informal{equation,table,example,figure}
>      and make title on all those elements optional.
> 
> Option 1 is probably easier for users and for tools, so I'm inclined
> to go that way at the moment. The only advantage to option 2, really,
> is that DocBook becomes four elements smaller. But the semantic
> disjunction is probably too high a price to pay.

For the record, even though many equations do actually have names,
in the scientific literature I think you will find exactly zero instances 
of titles on equations (for that matter there would be no TOC equation 
lists iether). For this reason IMHO option 1 would actually be a backwards 
step hindering the adoption of DocBook amongst a broader
community. 

Customarily equation blocks fall into two classes, these being
numerically labelled and unlabelled equations. The existing equation and 
informalequation elements provide a useful method for distinguishing
between those cases and my hope is that they could be retained. 
Its a shame there isn't a third option:

    3. The equation element be shifted out from the formal list into 
        a group of its own, because in reality it has a completely 
        different usage model.

Alternatively, if option 2 was adopted could some other standardised
means be established to discriminate between labelled and unlabelled 
equation blocks?


$0.02
Doug