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.

----

Stephen D Green

On 1 July 2014 10:38, Costello, Roger L. <costello@m...> wrote:

Hi Folks,

Inside our brain information is in parse trees:

The parse trees are structured according to a grammar, such as the English grammar.

When I want to communicate information to you I linearize the parse tree and transmit the linearization (i.e., the sentence) to you. You receive the sentence and immediately reconstruct the parse tree and apply semantics to the parse tree:

So information is exchanged by linearizing a parse tree, transmitting the sentence, and at the receiving end reconstructing the parse tree.

This is true for humans as well as for web services: A web service has information in a DOM (parse) tree, it linearizes (serializes) the DOM tree into an XML string, transmits the XML string, and the receiving web service reconstructs the parse tree and then applies semantics to it:

 

Neat!

/Roger