https://learn.microsoft.com/fr-fr/dotnet/api/system.web.ui.webcontrols.basevalidator.determinerenderuplevel?view=netframework-4.8.1
BaseValidator.DetermineRenderUplevel Method (System.Web.UI.WebControls) | Microsoft Learn
Determines whether the validation control can perform client-side validation.
system webmethoduimicrosoftlearn