🚀 go-pugleaf

  I like Dan's distinction between structural and formatting markup, 
but I propose we avoid assuming that:

>Structural markup is an abstraction of formatting markup. 

  The reason is that some presentational effects are not related to 
structure, but are just there because they are pretty or whatever.  
For example, indenting second and following paragraphs might be 
considered to be purely presentational, and with no structural 
relevance.

  Eliot says in a followup message that there is a many-to-one
relationship between presentation and structure; I'm suggesting 
that the relationship is actually many-to-many, and that the 
derivation of presentation from structure is not mandatory, but
simply common. 

-Darrell.