UniqTag is used to abbreviate gene sequences to unique and stable identifiers. It selects a representative k-mer from the sequence of each gene to be used as a systematic identifier for that gene. Unlike serial numbers, these identifiers are stable between different assemblies and annotations of the same data without requiring that previous annotations be lifted over by sequence alignment.
Shaun D. Jackman, Joerg Bohlmann, İnanç Birol (2015) UniqTag: Content-derived unique and stable identifiers for gene annotation. PLOS ONE, doi:10.1371/journal.pone.0128026.