================================================================================
longtable environment
================================================================================
foo
\begin{longtable}{l|c|r}
bar
\end{longtable}
wibble
--------------------------------------------------------------------------------
(document
  (text)
  (tabular_env
    (begin
      (cs)
      (group (l) (name) (r))
      (group (l) (text) (r)))
    (text)
    (end
      (cs)
      (group (l) (name) (r))))
  (text))

================================================================================
longtable environment with position
================================================================================
foo
\begin{longtable}[t]{l|c|r}
bar
\end{longtable}
wibble
--------------------------------------------------------------------------------
(document
  (text)
  (tabular_env
    (begin
      (cs)
      (group (l) (name) (r))
      (brack_group (lbrack) (text) (rbrack))
      (group (l) (text) (r)))
    (text)
    (end
      (cs)
      (group (l) (name) (r))))
  (text))