DateTime formats C#
string format = "dd.mm.yy";
date=DateTime.ParseExact (current.Substring(aiRule.AiLength), format, CultureInfo.InvariantCulture);

string Format =  "dd.MM.yy"


 mm is for showing minutes

 MM is for showing months..

string format = "dd.MM.yy";
string date = "27.10.11";
DateTime result;
result = DateTime.ParseExact(date, format, CultureInfo.InvariantCulture);