SC09: Detection of control characters. SC09.1 Test that control characters are detected and replaced by "?". SC09.2 Test non printable that has a mnemonic. There is a tab between these two bars | | which should come out as "?". The above error message should contain the mnemonic "HT". SC09.3 Test non printable that has no mnemonic. There is a non-mnemonic control character between these bars |ê|.