Can someone explain the body of the rest api to add users to groups?

Question

Can someone explain this body to me? Multipart question to get to a single action (add).

{ '__metadata': { 'type': 'SP.User' }, 'LoginName' : 'i:0#.w|domain\\user' }

1. Specifically 'i:0#.w|domain\\user' what are literals and what are variables?

2. Is the 0 a literal or a user id?

3. Why .w? when I inquire / interrogate SharePoint our users come back .f, not .w!

4. For |domain\\user, is this a literal? If so how do you specify the actual user you are trying to add?

5. If |domain\\user, is not a literal then was does it look like? |ad.myuniversity.edu\\myuser ... or ... |ad.myuniversity.edu\\myuser@ad.myuniversity.edu

Answer 1

What you are looking for is the Claims Username Format

<IdentityClaim>:0<ClaimType><ClaimValueType><AuthMode>|<OriginalIssuer (optional)>|<ClaimValue>

Where:

<IdentityClaim> indicates the type of claim and is the following:
“i” for an identity claim
“c” for any other claim

<ClaimType> indicates the format for the claim value and is the following:
“#” for a user logon name
“.” for  an anonymous user
“5” for an email address
“!” for an identity provider
“+” for a Group security identifier (SID)
“-“ for a role
“%” for a farm ID
“?” for a name identifier
"\" for a private personal identifier (PPID)
"e" for a user principal name (UPN)

<ClaimValueType> indicates the type of formatting for the claim value and is the following:
“.” for a string
“+” for an RFC 822-formatted name

<AuthMode> indicates the type of authentication used to obtain the identity claim and is the following:
“w” for Windows claims (no original issuer)
“s” for the local SharePoint security token service (STS) (no original issuer)
“t” for a trusted issuer
“m” for a membership issuer
“r” for a role provider issuer
“f” for forms-based authentication
“c” for a claim provider

<OriginalIssuer> indicates the original issuer of the claim.

<ClaimValueType> indicates the value of the claim in the <ClaimType> format.

http://social.technet.microsoft.com/wiki/contents/articles/13921.sharepoint-2013-claims-encoding-also-valuable-for-sharepoint-2010.aspx