The RPC_SID structure is an IDL representation of the SID type (as specified in  section 2.4.2) for use by RPC-based protocols.

 typedef struct _RPC_SID {
   unsigned char Revision;
   unsigned char SubAuthorityCount;
   [size_is(SubAuthorityCount)] unsigned long SubAuthority[];

Revision: An 8-bit unsigned integer that specifies the revision level of the SID. This value MUST be set to 0x01.

SubAuthorityCount: An 8-bit unsigned integer that specifies the number of elements in the SubAuthority array. The maximum number of elements allowed is 15.

IdentifierAuthority: An RPC_SID_IDENTIFIER_AUTHORITY structure that indicates the authority under which the SID was created. It describes the entity that created the SID. The Identifier Authority value {0,0,0,0,0,5} denotes SIDs created by the NT SID authority.

SubAuthority: A variable length array of unsigned 32-bit integers that uniquely identifies a principal relative to the IdentifierAuthority. Its length is determined by SubAuthorityCount.