The diacritic that looks like two little two dots are called a trema, not an umlaut. An umlaut is a specific usage of the trema, best known for its use in Germany. A trema mark can also be a diaeresis, which indicates that two letters are to be read separately. "Chloë" would be using a diaeresis.
Letters with tremas are also their own letters in some other languages (like in Finnish).
This message was edited 6/24/2011, 11:18 AM