Descriptive versus procedural markup

Strongly procedural:

  <center>Chapter 2: The Marketplace</center>
  <block>Dear reader, it was all I could do not to <italic>shout</italic> with 
  delight at my own <italic>savoir-faire</italic> when I saw how easily
  I had made myself at home...</block>

Procedural with a nod towards the descriptive:

  <block class="head">Chapter 2: The Marketplace</block>
  <block class="para">Dear reader, it was all I could do not to <span class="italic">shout</span> with 
  delight at my own <span class="italic">savoir-faire</span> when I saw how easily
  I had made myself at home...</block>

Descriptive with a nod to the procedural:

  <head html:style="text-align:center">Chapter 2: The Marketplace</head>
  <p>Dear reader, it was all I could do not to <emph html:style="font-style:italic">shout</emph> with 
  delight at my own <foreign html:style="font-style:italic">savoir-faire</foreign> when I saw how easily
  I had made myself at home...</p>

Strongly descriptive with an emphasis on structure:

  <div n="2">
    <head>The Marketplace</head>
    <p>Dear reader, it was all I could do not to <emph>shout</emph> with 
    delight at my own <foreign>savoir-faire</foreign> when I saw how easily
    I had made myself at home...</p>
  </div>

Strongly descriptive with an emphasis on the original presentation:

  <head rend="center">Chapter 2: The Marketplace</head>
  <p>Dear reader, it was all I could do not to <emph rend="italic">shout</emph> with 
  delight at my own <foreign rend="italic">savoir-faire</foreign> when I saw how easily
  I had made myself at home...</p>

Descriptive markup, broadly speaking, is about representing a source:

it looks backward to an original document
or it may express an original, digital idea
but either way, it is describing structures and ideas

Whereas procedural markup is about giving orders:

It specifies some output, some result
It always looks ahead to output, never back to a source

There’s clearly a continuum here: from purely procedural approaches on the one hand (in which the only thing we care about is giving instructions concerning output) to purely descriptive approaches on the other (in which the only thing we care about is the representation of the source

In accomplishing that representation we may or may not be interested in how the source looked: descriptive approaches may focus on structure or on presentation or both