"Wozzeck" has a little twelve tone music in it, but in his next works the twelve tone system is much more important. He wrote "Lyrical Suite" for String Quartet and a "Kammerkonzert" ("Chamber Concerto") in which the form is made up by mathematical rules. He liked to hide things in his music e.g. favourite numbers or letters from people’s names. These are like secret codes and, in later years, musicians have spent a lot of time trying to work out what Berg was trying to do.