Hello,

I would suggest to implement the server side validation by using either our built in features, or to modify the form controls according to your needs. To use our features in the server side validation, you can create a validation condition in any field editor, for example in CMS Site Manager / Development / Document types / <your document type> / Fields / <any field> / Validation. If you need additional checking, you can simply change the code of the change the code of the form control which is used to populate teh field, or create a custom one. For the client side validation you will have to create some custom javascript. If the form is on the live site, then the Javascript web part can be used to insert your code into your page.

Best regards,
Boris Pocatko