text: It does not work. I just tried to change the DisplayName from "Tag Page" to "Tag-Page" (in case it was the space that did it), but that didn't have any effect.
  Maybe it is simply because my TagPage has PageData as base class...?
  [ContentType( DisplayName = "Tag Page", GUID = "e36d32f2-34e2-45e7-ae3d-cfe853282f01", Description = "Tag landing page")] [AvailableContentTypes(Availability.None)] public class TagPage : PageData { }
  This text is fetch from a language file that is an embedded resource in EPiServer.Cms.Shell.UI.dll. You can change this by adding the following to one of your language files:
  <language name="English" id="en"> <episerver> <cms> <widget> <contentreferencelisteditor> <allowedtypes>You can add these types, dude!</allowedtypes> </contentreferencelisteditor> </widget> </cms> </episerver> ...
  This will change the text for all content reference list editors though.
  Ah,
  I misunderstood your question.
  To change the [Type] values, add localizaed values to your language file. For Your "Tag page", it would be something like:
  <contenttypes> <tagpage> <name>Tag page</name> <description>Something something something</description> </tagpage>
  Using "DisplayName" does not work for this purpose
  Does anyone know how to customize the part where it says “You can add these content types [Type]” in the editor when using a list of content references?
  Where does [Type] come from, and how can it be changed?
  Mine just says “Page” and it is quite misleading..