This has confused me also.
I've extracted the applicable sections of the law below:
d) any of the weapons, or
functioning frames of receivers of such weapons, or copies or duplicates of such weapons, in any caliber, known as:....
(iv) Colt AR-15;
e) provided, however, that such term does not include: ...
(v) a semiautomatic rifle, a semiautomatic shotgun or a semiautomatic
pistol
or any of the weapons defined in paragraph (d) of this
subdivision lawfully possessed prior to September fourteenth, nineteen
hundred ninety-four.
The way I see it...(d) defines an aw as including functioning frames of receivers.
(e) v...exempts weapons defined in (d) if they were possessed pre 9/14/94. Therefore, functioning frames and receivers are exempted if possessed prior to 9/14/94.
Seems clear as mud to me!
Whisky19