Which ironically makes Agile even worse at times by forcing developers to implement incomplete spec, parts of which are often rewritten over and over again everytime the PM talks to the client.
I remember having to deal with this and other identifiers like NIF and NIE while working on the academic titles homologation platform for the MCIN. I didn't understand why it wasn't used as, not necessarily PK, but an identifier logging in. Thanks for letting me know that the hellish time spent integrating Cl@ve wasn't in vain.