I often use binary data for usual plotting.
I think it is useful that xticlabels is permitted for binary data too.
Although string values can't be stored in gnuplot's binary data,
it will be possible to use with gprintf or to use in the following code taken from the help of xticslabel.
plot "data" binary record=100 format="%i%i%i" using 1:2:xtic( $3 > 10. ? "A" : "B" ) with points