2.2.5.2 PrincipalTypes
This type enumerates the set of types of SAML principals. The schema for this type MUST be as follows:
<simpleType name="PrincipalTypes">
<restriction base="string">
<enumeration value="Self" />
<enumeration value="Scope" />
<enumeration value="Authority" />
</restriction>
</simpleType>
Self: Indicates that the principal is this STS server.
Scope: Indicates that the principal is a SAML Service Provider, identified by an Entity Identifier, as per [SAMLCore2] section 8.3.6.
Authority: Indicates that the principal is a SAML Identity Provider, identified by an Entity Identifier, as per [SAMLCore2] section 8.3.6.