These ideas aren't original, and I haven't given them any SGML
 dress.  I'd be interested in hearing from anyone who's already
 done a logical-table DTD (or who has constructed a useful tool
 for composing such a table).
 This exposition needs example text, which is *entirely fictitious*.
 I'm posting it separately to html-wg and davenport; apologies to
 those who get two copies.
 1. The table's title is "How to convert Heritage documents to SGML"
 2. It has two dimensions, named abstractly as Red and Blue.  
 3. The red dimension deals with the following heritage formats,
    to which header/stub text is attached:
    RTF="Raunchy Text Format"
    ASCII="American Standard Call-It-Input"
    Handwriting="Handwriting"
 4. The blue dimension deals with the following DTDs:
    ISO 007="NASA DTD"
    PulpBook="PulpBook DTD"
    DTDDTDOC="DTDDTDOC"
 5. The cells or entries are specified as follows:
 "Use the filter that comes with your word processor"
 Red=RTF
 Blue=ISO 007
 "Cut and paste into a template"
 Red=ASCII
 Blue=ISO 007
 "Input from scratch"
 Red=Handwriting
 Blue=ISO 007
 "Ask a couch potato"
 Red=RTF
 Blue=PulpBook
 "Give up"
 Red=ASCII, Handwriting   [note: this is a span]
 Blue=PulpBook
 "Ask Chairman Bill"
 Red=RTF
 Blue=DTDDTDOC
 
 "Add tagging to your existing document"
 Red=ASCII
 Blue=DTDDTDOC
 "Rewrite carefully and watch your spelling"
 Red=Handwriting
 Blue=DTDDTDOC
6. Identify the presentational dimensions for the abstract names 
   given for the cells:  Red=x  Blue=y .  That means that the
   column headers will read (in an order yet to be specified):
   "Raunchy Text Format" "DTDDTDOC" "NASA DTD"
7. Identify the order in which the headers and stubs will be
   presented:
   Red="RTF, Handwriting, ASCII"
   Blue=alphabetical
8. Now all the info needed to determine the general layout of
   the table has been provided (did I miss anything?).  Rendering
   is probably more complicated than for tables described according
   to their appearance, but note that the cell info can be given 
   in any order, the axes and order of columns and rows are easy
   to change, and the model is easily extended into additional
   dimensions (for this table, the Yellow dimension might be
   "Money available for the job").
   
   Additional help may be required from a style sheet in order to 
   determine such things as column width and justification; this
   info can be keyed to the abstract names of the dimensions, the
   header/stub specifications, or the cells themselves.
   
-- Terry Allen (terry@ora.com)