Re: Relationship Taxonomy Questions

At 04:12 PM 1/22/97 -0600, Len Bullard wrote:
>With the understanding that some aspects of relationship linking are
>declared out of scope for this discussion, the following is submitted 
>as an example of prior work on the concepts of relationship forms 
>based on the HyTime ilinks of that period.  This is from the 
>extant MID documentation at http://navycals.dt.nav.mil/mid
>This source has the virtue that it is implemented and works 
>based on the HyTime of that time.  So where one wants both 
>relationship maintenance and behavioral interoperability, it 
>serves as an example of a viable approach.

The MID is interesting, both in the design approach and the fact that it
works and is freely available (your tax dollars at work).

I'm not convinced that the MID approach of using of hyperlinks that
represent direct transition types is necessarily the best way to design
such a thing.  However, since it works, I certainly can't say it's a failed

My personal feeling is that this problem would be better served by
providing semantic (rather than behavioral) types for the relationships
among information units and then appling transitional rules based on the
semantic types.  For example, in a procedure (which is what IETMs present),
information units (steps, subprocedures, part descriptions, etc.) can be
related based on their roles in the procedure: prerequisite, optional,
explanatory, supporting, alternate, etc.  These types represent the way the
author of the procedure thinks about the the information (you must perform
step 1 before step 2, you cannot skip step 3, procedure X is a prerequisite
for procedure Y) and reflects the reality of the procedure.  These
relationship types then naturally translate into particular behaviors based
on the *regulatory* implications of these semantic relationship (the whole
point of IETMs being to enforce the codified rules for how maintenance
procedures must be performed--i.e., if a step is prerequisite for another
step, it is against military rules not to perform that step).

Thus, instead of scripting the playback of a procedure, its playback should
be inherent in the rhetorical relationships in the information (or in one
use-scenario view of it) relative to a set of relationship-to-behavior
mappings (ie. military rules vs. shadetree mechanic rules).

But this is not intended to start an argument over ITEM and MID design (at
least not here), only to show that there are different ways to think about
link types and the relationship of link types to behaviors.  There is
definitely a continuum between purely behavior-related link types and
purely semantic link types.

But note that even in the MID, even though you have a link type of goto,
the specific user interface expression of that link type is dependent on
the configuration of the IETM viewer, so the MID doesn't really standardize
the behavior specification, it just adds another layer of abstraction that
further isolates the details of a particular behavior implementation from
the data to which the behavior is applied.


W. Eliot Kimber (eliot@isogen.com) 
Senior SGML Consulting Engineer, Highland Consulting
2200 North Lamar Street, Suite 230, Dallas, Texas 75202
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