Your description seemed correct to me
>
>However, one thing that doesn't seem clear is what happens to the
>ActionSlots defined in TokenGroupItems. Where do they go, and which one
>gets called by CallActionSlot?
>
>My understanding is that the actionslots are statically associated
>with cells rather than list items. Therefore, although there is a
>syntactic link with a specific visible, there is no link during
>execution. This interpretation appears to agree with Tom Schwengler's
>Technical FAQ.
Yes, I asked this question to Tom Schwengler about one year ago and had
interesting discussion about this with him and Wataru Kameyama. You can
look at our discussion in the MUG archives at
http://www.fokus.gmd.de/ovma/mug/archives/mailarchive-old/
The subject was "MHEG Tech FAQ" and it was the end of January and beginning
of February 97.
>This is quite an important point as both alternatives offer
>functionality that could be useful, and indeed I have seen test
>scripts that use both sorts of functionality:
>
>I'm fairly sure the first option is the intended behaviour, but:
>
>1. I would like confirmation of this.
You are right, Wataru explained me why the other assumption doesn't make sense.
>2. This could be added to the MTF issuelist. Some sort of explicit
> explanation of this mechanism could be added to the specification.
That's what I asked for but Wataru didn't find the standard ambiguous in
this area. The only WG12 resolutions is 4 about unused cells for which I
asked what an MHEG engine should do when the token would be held by a cells
that has no item attached. WG12 agreed that this need some technical
clarifications even if Wataru considered that it is an application domain
issue, not an MHEG-5 one.
>
>3. Thre is no way of specifying the Actionslots for an initially
> empty cell. As a work-around, I would suggest using
> ObjectNumber 0 to represent 'no initial contents' in
> TokenGroupItems.
That's true. I remember that someone suggested to be able to fill the
tokenGroupItems list with null in order to define actionslots to an
initially empty listGroup. This could be a new suggestion for the WG12
recommendations.
In the meantime, it is possible to fill the listGroup with some dummy
visible items and to delete all items when the scene is running.
>
>
>I suppose this leads on to Resolution 4 in the MHEG Task-Force
>issuelist: Handling of unused Cells in ListGroup objects.
Not exactly. The resolution 4 rather agree about needed clarification for
actions targeted to an unused cells (e.g. callactionslot, move, moveTo,
scrollItems). It does not concern the way to define an actionSlot for an
empty cell IMHO.
>
>Well, if actionslots are linked to cells then I would say the
>behaviour is:
>
>CallActionSlot performs as normal with empty cells. The cell is
>still there, even if it has no contents, so it is valid to perform
>the actions.
That's also the opinion of Wataru on this point, if I remember well.
HTH,
Emmanuel
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Emmanuel BEUQUE mailto:ebeuque@pratique.fr
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