What is the purpose of nameidentifier claim?

Question

What the claim of type http://schemas.xmlsoap.org/ws/2005/05/identity/claims/nameidentifier should be used for?

This is the main question, and here are

Answer 1

The nameidentifier claim should be used for getting a unique user name.

For Windows Authentication:

http://schemas.xmlsoap.org/ws/2005/05/identity/claims/nameidentifier domain\warlock

http://schemas.xmlsoap.org/ws/2005/05/identity/claims/name 0#.w|domain\warlock

domain\warlock is a Windows Login name

For Claims Based Authentiacation:

http://schemas.xmlsoap.org/ws/2005/05/identity/claims/nameidentifier warlock@localhost.com

http://schemas.xmlsoap.org/ws/2005/05/identity/claims/name 05.t|myidentityprovider|warlock@localhost.com

email was specified as the Identifier Claim

As you can see .../identity/claims/name describes name and identity provider as well.