public bool SetNewParameterToInstanceWall(UIApplication app, DefinitionFile myDefinitionFile)
{
// create a new group in the shared parameters file
DefinitionGroups myGroups = myDefinitionFile.Groups;
DefinitionGroup myGroup = myGroups.Create("MyParameters1");
// create an instance definition in definition group MyParameters
ExternalDefinitionCreationOptions option = new ExternalDefinitionCreationOptions("Instance_ProductDate", ParameterType.Text);
// Don't let the user modify the value, only the API
option.UserModifiable = false;
// Set tooltip
option.Description = "Wall product date";
Definition myDefinition_ProductDate = myGroup.Definitions.Create(option);
// create a category set and insert category of wall to it
CategorySet myCategories = app.Application.Create.NewCategorySet();
// use BuiltInCategory to get category of wall
Category myCategory = app.ActiveUIDocument.Document.Settings.Categories.get_Item(
BuiltInCategory.OST_Walls);
myCategories.Insert(myCategory);
//Create an instance of InstanceBinding
InstanceBinding instanceBinding = app.Application.Create.NewInstanceBinding(myCategories);
// Get the BingdingMap of current document.
BindingMap bindingMap = app.ActiveUIDocument.Document.ParameterBindings;
// Bind the definitions to the document
bool instanceBindOK = bindingMap.Insert(myDefinition_ProductDate,
instanceBinding, BuiltInParameterGroup.PG_TEXT);
return instanceBindOK;
}