The PUID is the primary key that uniquely identifies a .NET
Passport member. It is composed of a combination of two attributes,
MemberIDHigh (represented in the passport node as the
puidHigh attribute) and MemberIDLow (represented as
puidLow). The PUID identifier is comprised of this
combination due to lack of general support for 64-bit internal data
types. For more information, see the .NET Passport SDK.
The PUID can either be passed with the request or automatically
generated by MPF based on the security context for the calling
user. The .NET Passport service called by the request uses the PUID
to authorize access.