Mortgage duty is not imposed on the following—
(a) a mortgage of a mortgage-backed security or release of mortgage of a mortgage-backed security;
(b) a mortgage of a mortgage or pool of mortgages or part of a pool of mortgages for creating, issuing, marketing or securing a mortgage-backed security—(i) to a person entitled to a mortgage-backed security or a trustee or agent for a person entitled to a mortgage-backed security; or(ii) by or to a person who issues, makes or endorses a mortgage-backed security; or(iii) to a person who provides security, whether as guarantor, surety or otherwise, to a person entitled to a mortgage-backed security or a trustee or agent for a person entitled to a mortgage-backed security;
(c) a mortgage of an instrument—(i) issued or made for creating, issuing, marketing or securing payments under a mortgage-backed security; and(ii) that is of a class prescribed under a regulation.