Hi Roger
I love your choices of topics and you unstoppable, determined
effort to get to the bottom of things regarding XML.
I would posit that XML is a system for making 'affordances'.
Affordances can take many forms, many of which relate to
uses of symbols facilitated by the writing system and, more
recently in history, the printing system. So I would posit that
XML, like its predecessors writing and printing, is a system
for creating affordances.
By 'affordances' we mean devices we humans love to use to
get something done like opening a door or celebrating a
wedding. For the former a typical affordance is a door knob
or door handle. We know what one is for just by looking at
it, and with minimal learning, perhaps from observing others.
For the latter we have, for example, the affordance of a
wedding card. A most basic affordance is an extended hand
with the intention it be followed by a hand shake and perhaps
friendship or agreement of some mutually understood kind.
In all cases the affordance has the concept of mutually
shared understanding and at a fairly simple level so as to
have potential for wider adoption than the immediate users.
With a wedding card, in the UK it is a card folded in two with
the opening on the right and a greeting usually printed and
generic on the front and space inside for individual hand-written
greetings and / or names. It is easy to understand where
to add your name and might be passed around for other names.
Etcetera.
I posit that XML is similar to the system of artefacts and
conventions which allows the production of a greetings card:
Similar, or even more so, parallel to the writing and printing
systems, by design, I think, so that it allows the replacement
of written and printed affordances, and, moreover, it allows
the capturing of most or all essential features of a written
and / or printed affordance.
How this relates to your idea is that I think an affordance
doesn't really linearise a human thought so much as the
affordance is transferred into the human mind as a set of
mechanisms which the human can combine with their
thoughts in such a way that they can be transferred to the
affordance within some set of tolerances shared by others.
Then the affordance can facilitate its intended outcome
within a similar set of tolerances; and all this with the hope
of the proper outcome being achieved due to the common
understanding of general thought processes.
Affordances share qualities such as significance (they
have a feature which signifies their purpose clearly), some
follow-on action, and facilitation of the purpose they
signifiy. XML markup has the potential for each of these.
It has semantics which signifies its purpose, usually
embodied in its syntax, the existence of its instances
usually has a clear follow-on action or set of actions to
be performed and in these actions it usually facilitates
the final outcome which is its purpose.
