Identitag relational schema. This figure provides a schematic view of the Identitag tables and their relationships. Identitag can be depicted as three interconnected modules represented in this figure. For a more precise description see data dictionary (available on Identitag web site). The term "Species" could be replaced by any specific species for which transcript sequences are available. The different sources of information needed for completing Identitag are also shown. The minimum number of files consist of : one file containing tag sequences (extracting from ditag concatemers with a software like SAGE 2000), a Fasta file containing transcript sequences from the species considered and a file containing results of their comparison with protein databanks (using BLASTX).