aggregator_categorize_items_validate in modules/aggregator/aggregator.pages.inc
Validate aggregator_categorize_items form submissions.
date_validate in includes/form.inc
Validates the date type to stop dates like February 30, 2006.
filter_form_validate in modules/filter/filter.module
Validation callback for filter elements in a form.
install_configure_form_validate in ./install.php
Form API validate for the site configuration form.
password_confirm_validate in includes/form.inc
Validate password_confirm element.
_form_validate in includes/form.inc
Performs validation on form elements. First ensures required fields are completed, #maxlength is not exceeded, and selected options were in the list of options given to the user. Then calls user-defined validators.