Glossary

The terms that come up when you share an ID document, explained in one line. They're the same ones the app's "What do I cover?" guide uses.

MRZ

Machine-readable zone: the lines of characters on the back of the DNI (or the bottom of a passport). They repeat the number, the name, the date of birth and the expiry date — covering a printed field while leaving the MRZ visible is covering nothing.

CAN

The 6-digit number on the front of the DNI that gives NFC access to the chip. Almost no process needs it: cover it by default.

Support number (IDESP)

The physical identifier of the DNI card. Accommodation providers and vehicle rental companies must register it (RD 933/2021); outside those cases, cover it.

CIP

The personal identification code on the health card: unique and lifelong (RD 183/2004). It's the data that identifies you in healthcare — it and your name are enough.

Social Security number (NAF)

Your employment affiliation number. Very sensitive: it's used for employment and benefits. Only HR needs it — never a gym or a summer camp.

AEPD

The Spanish Data Protection Agency (aepd.es), the authority that watches over how your data is used. In June 2025 it stated that accommodation providers cannot demand a copy of your DNI.

KYC

"Know your customer": the identity verification that Law 10/2010 requires from banks and fintechs. It's the only process where you shouldn't cover anything — mark the copy with the mosaic and black and white instead.