Each user within Metrici is represented by a row on the user table. This holds their user logon reference, name, and email address. The user logon reference is often referred to as the "user id", though internally the "user identifier" is the numeric unique key for the user row.
Each user also has a user node, system.USERS.userlogonreference, where userlogonreference is the user logon reference with all punctuation and special characters removed and converted to lower case. This allows aspects of the user, such as home node and account, to be managed as node data rather than as part of the user table.
Passwords are held on a separate user password table.