TSR

The Slave Register is a website self described as:

The Slave Register (TSR) provides a central place for the registration of slaves and submissives. Each registration is assigned a unique Slave Registration Number ("SLRN"), and owned submissives and slaves can display an ownership certificate. You can create and maintain a registration here on the www.slaveregister.com website.

SLRN's are also frequently converted to bar codes as well and applied as brands, tattoos, or on other paraphenalia through the website.