The easiest way to create a validation rule is by using the Validation Rule Editor. The editor is available under the File Menu. This is a picklist-driven interface intended to simplify adding validation rules to your form. It supports simple rules like Field_A must contain ink" to more complex rules like "If Field_B is equal to X then Field_B must not be empty". The editor even allows If...Then...Else validation rule creation.
See the form in the Attachments section for a few examples. Please consult the Validation Rule topic in the Mi-Forms Designer help system.
In addition to the Validation Rule editor
Posted in: Mi-Forms Designer