https://learn.microsoft.com/en-us/dotnet/api/system.web.ui.webcontrols.controlparameter.propertyname?view=netframework-4.8.1&redirectedfrom=MSDN
ControlParameter.PropertyName Property (System.Web.UI.WebControls) | Microsoft Learn
Gets or sets the property name of the control identified by the ControlID property that the ControlParameter object binds to.
property systemweb uipropertynamemicrosoftlearn