SAVEPOINT syntax again

Against CVS HEAD:

> test=# select version();
> version
> -----------------------------------------------------------------------------------------------
> PostgreSQL 8.0.0beta1 on i686-pc-linux-gnu, compiled by GCC gcc (GCC) 3.3.3 (Debian 20040401)
> (1 row)
>
> test=# begin;
> BEGIN
> test=# savepoint foo;
> SAVEPOINT
> test=# rollback to foo;
> ROLLBACK
> test=# rollback to savepoint foo;
> ERROR: syntax error at or near "foo" at character 23
> LINE 1: rollback to savepoint foo;
> ^
> test=# rollback;
> ROLLBACK

> test=# begin;
> BEGIN
> test=# savepoint foo;
> SAVEPOINT
> test=# release foo;
> RELEASE
> test=# savepoint foo;
> SAVEPOINT
> test=# release savepoint foo;
> ERROR: syntax error at or near "foo" at character 19
> LINE 1: release savepoint foo;
> ^

Comments:

1) We have a different syntax to the SQL200n draft (and Oracle by the
looks of it) for ROLLBACK. The draft says:

> <rollback statement> ::= ROLLBACK [ WORK ] [ AND [ NO ] CHAIN ] [ <savepoint clause> ]
> <savepoint clause> ::= TO SAVEPOINT <savepoint specifier>

2) We have a different syntax for RELEASE too. The SQL200n draft says:

> <release savepoint statement> ::= RELEASE SAVEPOINT <savepoint specifier>

3) Can the command tag for a ROLLBACK TO SAVEPOINT be different to the
command tag for a global rollback, so clients can distinguish the two
cases? ("ROLLBACK <savepoint specifier>" might be nice)

-O