1. A computer-implemented method, comprising: under control of one or more computer systems configured with executable instructions, receiving a set of adjective-noun pairs including a symbol table usable in determining a bit sequence corresponding to at least one adjective-noun pair of the set of adjective-noun pairs; determining a sequence of bit values by at least: selecting an adjective-noun pair from the set of adjective-noun pairs; and determining, based at least in part on the symbol table, the bit sequence corresponding to the adjective-noun pair, where the symbol table maps the selected adjective-noun pair to the bit sequence, the bit sequence including a set of bit values associated with a binary number; and using the bit sequence to identify an item corresponding to an identifying sequence.