| comment_validate | modules/comment/comment.module | Validate comment data. |
| contact_admin_edit_validate | modules/contact/contact.admin.inc | Validate the contact category edit page form submission. |
| contact_mail_page_validate | modules/contact/contact.pages.inc | Validate the site-wide contact page form submission. |
| contact_user_page | modules/contact/contact.pages.inc | Personal contact page. |
| system_send_email_action_validate | modules/system/system.module | Validate system_send_email_action form submissions. |
| update_settings_validate | modules/update/update.settings.inc | Validation callback for the settings form. |
| valid_email_address | includes/common.inc | Verify the syntax of the given e-mail address. |
