Chapter 5 is specific to mental health disorders. It consists of a series of codes that correspond with a particular mental illness. The disorders are listed consecutively and there are 11 sections. SZ, schizotypal and delusional disorders consist of codes F20-F29. Within each code there are also sub categories, for example, SZ is F20 but Paranoid SZ is F20.0 whilst Catatonic SZ is F20.2