[30a - 52 lines; 30b - 33 lines]
1)[line 5]מאמרM A'AMAR (MA'AMAR YEVAMIM)
See Background to 27:1.
2)[line 9]אין זיקהEIN ZIKAH
See Background to 26:14.
3)[line 20]ואיידי דחביבה ליה אקדמהV'AIDI D'CHAVIVAH LEI, AKDEMAH- and since it was precious to him (because it contains a Chidush), he (Rebbi) taught it first
4)[line 21]ומשנה לא זזה ממקומהU'MISHNAH LO ZAZAH MI'MEKOMAH- and the original Mishnah was not removed from its place even though it was indeed no longer necessary
5)[line 49]אמר רב אשי זאת אומרת יש זיקהAMAR RAV ASHI, ZOS OMERES YESH ZIKAH- that is, our Mishnah holds "Nesu'in Mapilim" (see entry #7 below), and if the Yevamah was married to the dead brother together with the Ervah even at the beginning of her marriage, she does not fall to Yibum. Since the Mishnah holds Yesh Zikah, even if the Yevamah was even Zekukah to the dead brother at the time that the Ervah was married to him, it is considered as though the two were married to the dead brother at the same time, and the Yevamah (who is not an Ervah herself) is considered a Tzaras Ervah and does not fall to Yibum.
6)[line 17]תבראTAVRA- (a) there is a contradiction (between the Mishnah on Daf 2b and the Mishnah on Daf 30a) (RASHI); (b) a word used as an oath (TOSFOS Kesuvos 75b DH Tavra, citing RABEINU CHANANEL)
7)[line 26]מיתה מפלתMISAH MAPELES / NISU'IN HA'RISHONIM MAPILIM
(a)When a man dies without children, a bond termed "Zikah" forms between his wife (or wives) and his brother (or brothers). The Zikah does not allow her to marry anyone other than one of her Yevamim (brothers-in-law), and it exists until one of them has performed either Yibum or Chalitzah (see Background to 1:2).
(b)Tana'im disagree over the point at which the suitability of the Yevamah for Yibum is assessed. Some Tana'im understand that it is determined at the time of her husband's death, when the Zikah is forged. This opinion is referred to as "Misah Mapeles" (the bond between a Yavam and Yevamah is formed at the time of her first husband's death). Others maintain that a Yevamah falls to Yibum only when she was suitable all throughout her marriage. This opinion is referred to as "Nisu'in ha'Rishonim Mapilim" (the bond between a Yavam and Yevamah is formed at the time of her first marriage).
(c)All of the above opinions agree that whether or not there is an obligation of Yibum depends on whether the dead husband was childless at the time of his death. All agree, as well, that only if the husband dies childless does "Zikah" take effect, and not if he divorces his wives. They argue over a number of specific Halachos in Yibum.
(d)In our Sugya, the Gemara explains that the question of Misah Mapeles / Nisu'in Mapilim affects the Halachah stated at the end of the Mishnah (Yevamos 2b). The Mishnah (Daf 2b) states that if one of the wives of the childless brother was a close relative to the Yavam, she and her Tzaros (co-wives) are exempt from Zikah, and do not need Yibum or Chalitzah. If the wife who was a relative of the Yavam dies or is divorced before the death of the childless brother, the Yavam is permitted to marry the Tzarah (co-wife) of the close relative. According to those who hold "Misah Mapeles," the marital status of the relative at the time of her husband's death establishes whether the Yavam may marry the Tzarah or not; if she was divorced a moment before the death, the Tzarah must do Yibum. According to those who maintain that "Nisu'in ha'Rishonim Mapilim," the entire history of the marriage of the deceased brother is taken into account in order to establish whether the Yavam may marry the Tzarah. If the relative of the Yavam was married to the childless brother together with the co-wife at any point during their marriage, the co-wife is exempt from Yibum. It makes no difference whether or not the relative was married to the childless brother at the time of his death or not.