Boer spends a significant portion of the introduction discussing the origin of the term "socialism with Chinese characteristics" from a philosophical perspective. He maintains that the utility of the term highlights that socialism is the center of contemporary Chinese politics and philosophy, not some new "ism" or holistic philosophical upheaval.
Chinese Characteristics … entail China's specific practice of Marxism, there era in which China finds itself, and China's culture and history.
Roland Boer
As for the origin of the term, it can be traced back to the Zunyi Conference of January 1935 which led to the sino-soviet split, and reinforced the desire to root the development of socialism as an expression of and framework for action, rather than a purely academic endeavor.
To this day the CPC maintains Marx's writings are a central axis upon which Socialism with Chinese Characteristics exists, but seeks to adapt and modernize the theory without imposing their particular revolutionary strategy onto developing socialist projects.
The "target" is the Chinese revolution, the "arrow" is Marxism-Leninism
Mao Zedong