On a database file, the designer uses chi and zho to tell simplified Chinese and traditional Chinese. It's hard to tell whether chi means the simplified one or traditional.
Seemingly, chi is derived from the first three characters of "Chinese", zho from the first three of "Zhōngwén".
The wiki page of Chinese language, as well as the following two links from ISO 639 documentation, chi and zho, all tell us that chi is ISO 639-2/B, where the B stands for bibliographic, zho being ISO 639-2/T, T for terminological. The explanation of the B and T codes does not shed any light on traditional-or-simplified information the either.
But there is nowhere that I can refer to showing which one representing the traditional Chinese.