NTSTATUS
RtlInitializeSid(
  IN  PSID Sid,
  IN  PSID_IDENTIFIER_AUTHORITY IdentifierAuthority,
  IN  UCHAR SubAuthorityCount
  );

Routine Description:

    This function initializes an SID data structure.  It does not, however,
    set the sub-authority values.  This must be done separately.

Arguments:

    Sid - Pointer to the SID data structure to initialize.

    IdentifierAuthority - Pointer to the Identifier Authority value to
        set in the SID.

    SubAuthorityCount - The number of sub-authorities that will be placed in
        the SID (a separate action).

Return Value: