datetime and timespan.

spi.c: functions to prepare/run and preserve plans for
       duration of transaction/session. Some data utilities.

and O'Reilly "lex & yacc" book claims ATT-lex has trouble with comments.

RelationBuildTriggers() & FreeTriggerDesc() in trigger.c

Fix up results labels on queries.
Update existing queries which now return good results.

Fix up results labels on queries.

Use #define symbols rather than integers for scanning states.

Add field to support "WITH TIME ZONE".

Add parsing for UNION and outer JOINs.
Implement SQL92 "WITH TIME ZONE".
Allow some reserved words as identifiers and column labels.
Clean up indentation and "orphan spaces and tabs".

Generate non-fatal warning only and proceed by ignoring clauses.

Include reserved words for string handling, outer joins, and unions.

Implement extended comments ("/* ... */") using exclusive states.
Modify definitions of operators to remove some restrictions on characters
 and character order.