What he's referring to is known to normal people as a cipher.
A process to substitute letters and symbols with others depending on the symbol your substituting it with, and for more complex ciphers, even the order.
Usually longer ciphers are numerically constructed with transformation matrices and their inverses.
Of course, to decipher a ciphered message you have to have some understanding of the cipher, and non-linear numerical ciphers are virtually impossible to figure out.
Considering how he used UTF-8 symbols rather than the typical ciphers which usually corresponds to to the regular alphabet and in some cases ASCII, I'd say that he's making his own incomplete cipher which is impossible to decipher due being underdetermined. Though I do suspect a cipher without emphasis on order.