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Subject: Re: [dita] Re: Comparison between DITA and S1000D

john_hunt@us.ibm.com wrote:
> Erik said:
> <<More generally, the DITA TC should recommend as a preferred approach 
> that human-readable topic content be modelled on a single type 
> hierarchy.  Of course, other kinds of content (for instance, invoice 
> data) would be a distinct type hierarchy.>>
> Yes, I agree. If there's potential to S1000D in adopting the DITA 
> architecture, then the DITA-ized S1000D would develop a type hierarchy 
> with a base type. The question then becomes, why not start with the DITA 
> base type? If not the DITA base type, then what's needed in the DITA 
> base type to make it work?
> The advantages that ensue from a common base type are significant. It's 
> this "specialization with a fallback" that enables much of the power of 
> DITA's topic-based reuse model, and which distinguishes it from other 
> approaches. It's what makes it possible to say that with DITA, it's 
> possible to exchange, integrate, and reuse content across disparate 
> information domains, such as IT, pharmeceutical, military, aviation, 
> telecommunications, etc. This is one key, clear advantage DITA brings to 
> the table. I'd hesitate to weaken it by splitting the DITA architecture 
> model from its typing hierarchy and the common base it provides.

This is a laudable goal but I think that it's important to keep a couple 
of things in mind:

1. The DITA modules as currently defined are not suitable as the base 
for this sort of very wide use as the underpinnings for technical 
documentation. This is because the current modules are too narrow in 
their constraints. For example, none of the DTDs I use in my daily work 
for creating technical documents can be directly derived from DITA 
because I use (and want) more levels of containment than DITA can 
provide for. This will be true for almost any DTD I have had a hand in 

2. The actual value for interchange of an architecture that is 
sufficiently general to actually be the underpinning of most or all 
technical documentation DTDs is questionable--any DTD that general will 
also be able to offer limited value in terms of default presentation 
behavior, clear semantics, and so on.

My experience based on trying to enable interchange and interoperation 
of markup-based documents at large scales over the last 15 years is that 
we, as a community, tend to overvalue interchange and undervalue meeting 
of local requirements, largely overestimating the amount of re-use and 
interchange that will (or can) actually happen.

Part of this may be because the technology was simply not there to allow 
truely wide-scope interchange but I think it has more to do with the 
fact that the actual cost of enabling and doing interchange is hight 
enough that business requirements and realities tend to change before 
enabling systems can be either built and deployed or used long enough to 
realize their benefits, which are, by necessity, long-term.

This is not to say that interchange is not valuable or possible, just 
that as the intended scope of interchange increases the cost rises 

Architectural mechanisms like DITA make it *possible* to do wide-scope 
interchange but they don't necessarily significantly reduce the cost 
because most of the cost factors are from infrastructure and management, 
not from the act of interchange itself.

Or said another way, something like DITA makes what was impossible 
possible but it doesn't necessarily make the expensive cheap. This is my 

For example, in safety-critical applications such as aircraft 
maintenance information, the importance of information correctness is so 
high that it must be carefully reviewed and checked at every stage. So 
even when information can be transparently interchanged between 
organizations it must still be inspected by humans. This inspection 
requires lots of human effort, whose cost far outstrips any cost that 
would occrue from not having to transform or re-author the data, such 
that any effort made to eliminate transforms or re-authoring, while 
measurable, often ends up being over-optimization.

Note also that I'm not saying that there's anything wrong with the DITA 
modules as they exist--clearly they are very useful within the scope of 
application for which they were defined. But they are not anywhere near 

I think it is the rare use case where data is actually interchanged in 
volume across industries to the point where, for example, S1000D content 
would need to be re-used in a pure-DITA environment.

Also, I think it's easy to overstate the cost of transforms relative to 
the cost of defining, maintaining, and applying specifications of wide 

That is, when the structural and semantic differences between the source 
and target are small, as they tend to be with technical documents, it is 
almost always less expensive to create local transform-based solutions 
for interchange than to re-engineer either the source or the target (or 
both) in order to enable direct interchange.

For example, a general S1000D-to-DITA transform could be implemented by 
one person in a matter of hours. It would be a monumental undertaking to 
ask the entire S1000D community to re-engineer their entire XML 
environment--DTDs, document collections, internalized human experience, 
policies, processors, and so on--to move to a DITA-based solution.

Of course, if S1000D is just a specification with no real users yet, 
it's a different story and making it DITA-based *might* be compelling if 
a DITA-based document type can otherwise meet the local requirements of 
that community (which is not proven until tried).


W. Eliot Kimber
Professional Services
Innodata Isogen
9390 Research Blvd, #410
Austin, TX 78759
(512) 372-8122


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