Using the same example shown in Figure 2, the following three actions can be applied for the character " ' big)": (1) APP("'(big)"), appending "'(big)" to the last word "-¨(yālí, pear)" in the informal labeled sequence, which remain with the same POS tag "NN".
li and Yarowsky (2008) classified them into four types: homophone, abbreviation, transliteration and others.