The AUTH_SCHEME_VECTOR structure encapsulates a variable-length array of AUTH_SCHEME GUIDs that are stored consecutively. 

 struct
 {
   ULONG AuthSchemeArrayOffset;
   USHORT AuthSchemeCount;
 } AUTH_SCHEME_VECTOR; 

AuthSchemeArrayOffset: A ULONG type array of ordered AUTH_SCHEME GUID values, specified in section 2.2.2, that represents the security mechanism's ID in decreasing order of preference.

AuthSchemeCount: A USHORT that contains the count of AUTH_SCHEME values.