Schema validation with simple dom php classes, that will check the xsd file before the xml based forms will accept any submit. The ajax wrapper should work with widgets to show any validation error to the form user.
Acumen has gone through a near complete rewrite. Please see the Github page for details - https://github.com/AcumenProject
[OLD Description] Acumen is a simple, robust digital library system using PHP, MySQL, and Apache. Easy to set up and administer, does not complicate workflows, supports all browsers, and automatically creates and updates its own index database.