This is in partial reply to Stig Johansson's posting of 5 December
on temporal alignment.
It would not be at all difficult to separate out temporal alignment from
one-dimensional spatial alignment, calling the first
<tag>timeline</tag>, as in the Spoken Language Working Group's proposal
(in AI2 W1), and the second, say, <tag>spaceline</tag>. We could then
eliminate the <term>type attribute from what I called <tag>align and
deal with the fact that the two tags have nearly if not totally
identical content models and attribute lists by means of a parameter
entity, such as <term>%align;</term>.
Regarding the use of <tag>xref for <tag>pointer</tag>, I was following
up on a recommendation that came out of the Myrdal meeting to reduce the
number of distinct tags whose function is to point. To deal with the
problem of identifying what a particular <tag>xref is pointing to, I
suggested adding an <term>entity attribute, whose value is the name of
the entity being pointed to. Thus an <tag>xref pointing to a <tag>u
could look as follows: <xref element=u ...>, or, if the values of
<term>element were given in the DTD as a fixed list, simply <xref u ...>.
My suggestion to treat <tag>loc not as an empty tag (as <tag>pointer is
in AI2 W1) was based on the idea that it would be useful (but
<emph>not</emph> mandatory) to be able to point from the timeline to
the text as well as from the text to the timeline. In fact, the ability
to point from the timeline to the text (as in the original
<tag>alignment mechanism in P1) means that you can eliminate all
temporal reference from the text. All (and I do mean all) of the
alignment can be handled by pointers from the timeline to the text.
I am prepared to show this in detail with the toy examples that we
were using in Myrdal, and if there is interest I will post an example.
(It will be offered for publication in P2 or the subsequent tutorials.)
The same is true with spatial alignment; it is possible to indicate
line breaks and all the other stuff that can seriously clutter up a
document simply with pointers from <tag>spaceline</tag>.
And Rosta and I have been quietly conversing in the background, and I
think I have been able to resolve all of our differences, except for
what I take to be his ontological objection to <tag>loc not being an
empty tag. The other outstanding difference, namely my elimination of
the <term>since attribute, I have since been persuaded to restore, and
will post a revised DTD in which essentially all of the features of the
original <tag>timeline proposal appear, plus some others.
Stig's final paragraph is tantalizing. While Brian MacWhinney's
demurral may be <q>significant</q> it is not particularly helpful.
What would he like that we haven't provided? And Stig, why are you
not so pleased with your own proposals?