-- Warn when left-recursive symbols appear elsewhere, other than at the end
- of a production. Might have to special-case Newlines.
-- parser not to get into ERROR infinite loop
-- sort 'virtual' symbols to end
-- allow $xy instead of $3. Chooses shortest bodysym with xy in that order
- $xy_2 gives the second one
-- allow $TERM terminals to be listed. If so, extras are errors