What does Page_ValidationSummaries mean?

Hi,
When I view source of a web page I see this, can any one tell what this mean? & what they are using (type of controls)?

document.getElementById('ctl00_ContentPlaceHolder1_Enrollment_valSumCredCardDeposit').dispose = function() {
Array.remove(Page_ValidationSummaries, document.getElementById('ctl00_ContentPlaceHolder1_Enrollment_valSumCredCardDeposit'));
}




...