Let's install the plugin and see how it works:
mysql> install plugin html soname 'ha_html.so';
Query OK, 0 rows affected (0.00 sec)
Keep in mind that if a plugin was built statically into the server, it does not need to be installed.
mysql> create table test (number int, timestamp timestamp, string varchar(50)) engine=html;
Query OK, 0 rows affected (0.01 sec)
mysql> insert test values (1,null,"foo"), (2, "2010-01-02 03:04:05", "barbarbar"), (5,0,NULL);
Query OK, 3 rows affected (0.00 sec)
Records: 3 Duplicates: 0 Warnings: 0
mysql> select * from test;
+--------+---------------------+-----------+
| number | timestamp | string |
+--------+---------------------+-----------+
| 1 | 2010-06-29 18:23:18 | foo |
| 2 | 2010-01-02 03:04:05 | barbarbar |
| 5 | 0000-00-00 00:00:00 | NULL |
+--------+---------------------+-----------+
3 rows in set (0.00 sec)
It looks like it works. INSERT works, SELECT works, NULL values can be stored, and the TIMESTAMP column is...