RE: Terminology

>To take a simple example, the word 'schema' -- I have an understanding of 
>what this means in the context of XML, but it clearly also has a more
formal 
>meaning, as it can be applied to database design as well.  So what's the 
>definition of 'schema'?

Unlike a lot of these terms that we throw around, there is no solid formal
computer science definition of the term "schema." At least, none that I
could find, and I looked in a wide variety of textbooks and basic reference
works (C.J. Date, etc.). 

For a non-computer science dictionary definition, how's this from
http://agniweb.com/dict/dict.cgi?dict=*&strategy=*&query=schema: "An outline
or image universally applicable to a general conception, under which it is
likely to be presented to the mind." Gotta love it. Anyway, the common use
of the term schema means an expression of a document type's structure using
a specialized XML document, and the common use of "DTD" means an expression
of a document type's structure using the kinds of declarations described in
the XML 1.0 specification (<!ELEMENT...>, <!ATTLIST...>, etc.) 

Unlike "schema," "DTD" does have a more formal and precise definition (see
http://www.w3.org/TR/REC-xml#sec-prolog-dtd in the spec, under production
27) as a "grammar for a class of documents." What people think of as a DTD
is actually one expression of that grammar, and what people think of as
schemas is actually another expression of that grammar. 

>My question is, are there any books or online documents dealing with the 
>theory of 'information stuctures'?  Some kind of description of the ways in

>which information may be structured, and the advantages of doing it a 
>particular way?

The term "data structures" is more commonly used, but discussions of it
focus on the data structures available in various computer languages and how
to use them, not when. I used to like the term "information design" until I
found out that it's used to describe visual layout by the page layout types
who now design web pages. "Information architecture" is also popular, but
popular enough to become a buzzword and therefore often applied a bit too
widely. The design of a given system's "object model" is probably closest to
what you want; this will take you in the direction of the object-oriented
literature, and document designers (i.e. people analyzing information
components and their relationships, not the "information designers" picking
fonts and colors) can learn a lot from that world.

Bob DuCharme          www.snee.com/bob           <bob@  
snee.com>  "The elements be kind to thee, and make thy
spirits all of comfort!" Anthony and Cleopatra, III ii


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