On the MaltBlue blog Matt has posted the latest part of the "Zend_Form with Zend_Config" series, part four looking at using and configuring some form validators.

Welcome to the fourth and final part in the Zend Form Mastery with Zend Config series. Previously we looked at the basic form options, element and form wide prefixes, filters and element options. In this installment, we're going to look at configuring Zend Validators via our XML config. [...] To go in to all of them will take more time than is allowed in the confines of this article. So we're going to work through 5 of the more interesting and likely used ones.

He covers the validation for: email addresses, postal codes, seeing if a record exists in the database, IBAN validation and checking to see if a value is in an array. He gives XML examples for each of these validation methods including the definitions of options and error/feedback messages.