Re: Suggestion: A link model

At 3:24 PM 12/29/96, W. Eliot Kimber wrote:
>In HyTime, the anchor roles of a particular link type must be the same for
>all instances of the type *in the same document.*  This is partly because
>in the new HyTime design, addressing of anchors is done by attributes whose
>names correspond to the anchor roles--therefore the anchor role names must
>be unique within the type and they must be fixed or you couldn't declare
>the attributes.

    Steve DeRose and I have strongly argued against this mis-feature of
HyTime many times. It is a pointless restriction that means that one
_cannot_ define multi-ended links where the number of linkends is defined
by the application. I thought that this was slated to go away in the TC.
(At least I hoped there was a chance that someone would want to represent
pop-up menus as multi-ended links). I strongly urge that we not adopt this
"feature" of HyTime.

    I expect Eliot to claim that the above is false. I do not believe  that
composite anchors (discontinuous selections) are the same as multiple link
endpoints, and so I do not accept the proposal that he is likely to make. I
also think that _for XML_ this will not work, as I think that discontinuous
link endpoints (HyTime (unrevised) multlocs) should not be part of XML.
They are a bit too esoteric for our audience, I think.

>Note that we do now have way to indicate that it is *not an error* to for a
>given anchor role to consist of zero objects (i.e., that you can choose to
>not address anything for a particular anchor role).  That means that you
>can make any anchor-addressing attribute optional if it is not an error for
>that anchor to be null.

What is the syntax for this? In (uncorrected) HyTime, they are both lists
of IDs, in 1-1 correspondence, so you cannot "leave one out".

I really hope to get to read the TC soon, but I'd rather get a degree and
see XML on its way.

   -- David

I am not a number. I am an undefined character.
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