https://learn.microsoft.com/en-us/dotnet/api/system.web.ui.webcontrols.basedataboundcontrol.onpagepreload?view=netframework-4.8.1
BaseDataBoundControl.OnPagePreLoad(Object, EventArgs) Method (System.Web.UI.WebControls) |...
Sets the initialized state of the data-bound control before the control is loaded.
system webobjectmethodui