Hi,

The enclosed patch addresses the following short-comings as posted in 
the prior patch:

  - matrices are now properly rendered in row-order by the front-end 
manually descending through each row in the column ("pile") fields

  - a few scoping issue have been fixed

  - added ceiling/floor markers

  - diacritical combiners now working

The following is a link to all examples in "Typesetting Mathematics — 
User’s Guide (Second Edition)", Brian W. Kernighan and Lorinda L. 
Cherry, with a few additional examples.  (Note my mail on discuss@ and 
the missing underscore to the last example.)

   http://kristaps.bsd.lv/eqn-test.1.html
   http://kristaps.bsd.lv/eqn-test.1

Best,

Kristaps