How do i enter NULL in a table cell in the Enterprise Manager UI for table data entry?

I have a column defined as smalldatetime. Default length (4), and "allow NULLS" is checked.
In the Enterprise Manager UI, when i enter data into that table row, if i just tab past that column, all is well, and the value is represented in the UI as <NULL>.
The problem comes once i ever enter a date into that column. Say i have entered a date (all is well), and now i want to remove that entry and go back to NULL (after the date value has been committed, different entry session, say).
How is that done?
It seems to me, once a date has ever been entered into that column, now, if i try to remove it, i get the error "The value you entered is not consistant with the data type or length of the column, or over grid buffer limit". I have tried deleting the value, entering spaces, entering the string NULL or the string <NULL>; maybe some other tries as well, but none works, i always get that error message and am not allowed to proceed past that cell until i restore a date value to it. I want to get back to <NULL>.
Anybody know?
Thank you.
Tom

CTRL + 0 will do it.