Historical dates in Timestamp

Saluton,

I have a database with dates, some of which are historical dates.
When I wanted to enter May 28th, 812 I got an error message, had to
use 0812 for the year instead:

albert=> CREATE DATABASE test;
CREATE DATABASE
albert=> \c test
You are now connected to database test.
test=> CREATE TABLE dates (d timestamp);
CREATE
test=> insert into dates (d) values ('812-5-28');
ERROR: Bad timestamp external representation '812-5-28'
test=> insert into dates (d) values ('0812-5-28');
INSERT 81801 1

The same happens for BC dates:

test=> insert into dates (d) values ('812-5-28 BC');
ERROR: Bad timestamp external representation '812-5-28 BC'
test=> insert into dates (d) values ('0812-5-28 BC');
INSERT 81802 1

Is it really reasonable to enforce that the number of years is four
digits at least?

I'm running:

test=> SELECT version();
version
--------------------------------------------------------------------
PostgreSQL 7.0.2 on i586-pc-linux-gnulibc1, compiled by gcc 2.95.1
(1 row)

Bye,

Albert.