The //TRANSLIT feature of iconv is not documented in the glibc manual, although it is documented in the manual for the separate libiconv <URL: http://www.gnu.org/software/libiconv/documentation/libiconv/iconv_open.3.html >.
Also //IGNORE string is not documented.
FWIW, the upstream manual page documents these now: http://man7.org/linux/man-pages/man1/iconv.1.html