https://resources.arcgis.com/en/help/arcobjects-net/componentHelp/002n/002n000002t2000000.htm
IGPParameterEdit.ParameterType Property (ArcObjects .NET 10.1 SDK)
propertysdk
https://resources.arcgis.com/en/help/arcobjects-net/componentHelp/002n/002n000002ss000000.htm
IGPParameterEdit.DisplayName Property (ArcObjects .NET 10.1 SDK)
displaynamepropertysdk
https://resources.arcgis.com/en/help/arcobjects-net/componentHelp/002n/002n000002s8000000.htm
IGPParameterEdit.Altered Property (ArcObjects .NET 10.1 SDK)
alteredpropertysdk