The condition that will mark the control as invalid and prevent the form from being submitted if the condition expression evaluates to TRUE. If the expression evaluates to FALSE, the rule will not be triggered. The formula builder button (to the right of the Condition field) can be used to aid construction of condition formulas. The form will not be submitted if the validation rule evaluates to TRUE.

To use an expression that needs an operator, use from the following:

String literals must be contained in double quotes (e.g. Option=="High").

== is equal to

=== is exactly equal to (value and type)

!= is not equal

!== is not equal (neither value or type)

> is greater than

< is less than

>= is greater than or equal to

<= is less than or equal to

&& and

| | or

! not

Use the {Self} variable (available in the Named Controls tab in the Formula Builder) to reference the value in control associated to a rule within a condition

If comparing two date controls you can (DateControl1 <= DateControl2) this is to mean that DateControl1 must be greater in order to be valid and allow submit.

Andrew,

Can't say how valuable this post has been. Thanks for putting it together. I've referenced it in at least 3 answers so far.