With this feature you can create your own Javascript validation function and pass the name to our extension. The extension will eval your function and return the value your function return. The name of your function can contain only letter and number. The extension will call your function and pass the name of the text fied.

This is an example:
<script language=javascript>
function yourOwnFunction(name){
//Here your validation code
//name is the name of the field you must validate
//the name is passed from out extension

//Here your validation code
}
</script>
This function must return a true or a false

This is what you must write in the fied in the extension panel: