Capture at room temperature of a tag to its specific complementary EraCode was tested by use of a model extension system where one target with a 5Ј-iC was constructed and 50 tags were interchanged onto a targetspecific extender sequence. EraCodes were constructed by use of 9 -10 bases comprising 2-3 iCs. In an effort to minimize interference from naturally occurring sequences, EraCodes were designed to have no more than four naturally occurring bases in a row. In an effort to minimize code-to-code cross-hybridization, no two codes were allowed to contain the same series of more than four nucleobases in a row.