While this is somewhat simpler than identifying a "word", the completely naive approach of looking at every (overlapping) sequence of three bytes is non-optimal.
First language and mother tongue are overlapping concepts. It is the language identity of a nation or an individual that determines the mother tongue, but not the sequence of acquisition.
第一语言与母语是交叉概念，决定母语的不是语言获得的顺序，而是民族或自己的语言认同。
3
On space aspect, it shows overlapping of prototype basin and structural sequence of different types.