Halakhah for Song of Songs 5:6

With which phrases may a get be nullified? He could say "It is nullified!" "It is nothing," "This get will be ineffective," will not release her," "will not leave," "will not send her away," "will not divorce," "will be as a shard of pottery," or "Behold! It is as a shard of pottery." If he said any of those phrases or other similar ones, it is nullified. But if he said "this get is not a get," or "is not effective," "does not release," "does not send away," "does not divorce," "is as a shard of pottery," it is as if he said nothing. If he said "this get is nullified" but did not say "it" or said "this get has been nullified, in the past tense as in "had turned and gone" (Song of Songs 5:6), this is ambiguous.