Whenever the predicted symbol is unique, there is no need to encode it as the decoder generates the same model from the DTD and thus can generate the unique expected symbol.

The key caps may be printed differently, and the keyboard driver may encode a few more special cases, but the model is the same: Press a key to type a specific character.

In this article, we analyze the SOAP, introduce the mechanism of SOAP, including the encapsulation of structure, encode regulation and information exchange model.