Problems with array

Hello there!

I'm using postgresql 7.2.1.

I have a table and I need to create a type array field, this field must
have two dimensions, but when I alter the table, only create the field
with one dimension.

I do this:

alter table one_table add column column_added numeric[][];

And the table is altered, but when I get the description of this, only
one dimension of the array is defined.

Something is wrong or in the definition of an array only shows one
dimension whatever it has?

Tnanks in advance!

Salut.

Sonia