What is the point of the key parameter in ModelState.AddModelError in ASP.NET MVC?

Question

I\'ve added validation checks in my controller that modify the ModelState if the validation fails.

For example:

Answer 1

Sorry to Necropost. The above answers didn't have this detail that I thought was useful (it was what I was looking for!!)

In order to create 'Model Wide' Validation errors - then you simply add string.Empty as your Key.

e.g.

ModelState.AddModelError(string.Empty, "This is my Model Level Message");

Thanks to : http://www.tutorialsteacher.com/mvc/htmlhelper-validationsummary for the tip.