Facebook API: What is the maximum length of a “post” on a wall?

I looked through the Facebook documentation and can't find the maximum length that can be passed to the Facebook API?

If I pass the great value of the API using AJAX and using the PHP SDK, I get no error message or success message. (and no message on the wall).

I want to limit the user to the correct length in order to avoid any problems.

Thank you for your help,

Luke