https://learn.microsoft.com/en-us/dotnet/api/system.web.ui.webcontrols.rangevalidator?view=netframework-4.8.1&redirectedfrom=MSDN
RangeValidator Class (System.Web.UI.WebControls) | Microsoft Learn
Checks whether the value of an input control is within a specified range of values.
class systemweb uimicrosoftlearn