The Input Validator control uses objects based on the ValidationExpression class and its derived classes to set up validation for each compatible input component. 

The class hierarchy is as follows:

• ValidationExpression
• ValidationCriterion
• DataTypeCriterion
• ConstantListCriterion
• ConstantValueCriterion
• InputCellValueCriterion
• InputValueCriterion
• RangeCriterion
• RegularExpressionCriterion

For details on the derived classes, see Types of Validation Criteria.