the carrier of S in {the carrier of S} by TARSKI:def 1;
then [o,the carrier of S] in [:the carrier' of S,{the carrier of S}:] by ZFMISC_1:106;
then [o,the carrier of S] in NonTerminals (DTConOSA X) by Th3;
hence [o,the carrier of S] is Symbol of (DTConOSA X) ; :: thesis: verum