Gemara

66b: Rav Nechemyah brei d'Rav Yosef instructed Rabah bar Rav Huna to authorize a certain girl to collect a tenth of her father's estate (for her dowry), even from the frame around a millstone. (It is considered like land.)

(Rav Ashi): In Rav Kahana's academy, we collected even from rental of houses.

Kesuvos 50b (R. Chiya bar Yosef): Rav was Zan from Aliyah wheat.

Possibility #1: 'Zan' refers to Parnasah (dowry). 'Aliyah' refers to the estimation of how much the father would have given, like Shmuel;

(Shmuel): We assess the father's generosity to determine how much Parnasah to give to his daughters (from his estate after he died).

Possibility #2: 'Zan' literally means fed. 'Aliyah' refers to nice teachings said in the attic:

(R. Yitzchak bar Yosef): In the attic, they enacted that daughters be fed (also) from Metaltelim.

69b (Rava): The Halachah is, food for a widow and daughters, a Kesuvah, and Parnasah are collected only from land, but not from Metaltelim:

Rishonim

Rif and Rosh (Kesuvos 30b and 6:19): The Halachah is, Kesuvah, food and Parnasah are taken only from land, but not from Metaltelim. Nowadays, Chachamim of the Yeshivos enacted to collect the Kesuvah even from Metaltelim, so also food is collected from Metaltelim, for we hold that Tanai (stipulations of the) Kesuvah are like the Kesuvah. Parnasah is not a Tanai Kesuvah, so its initial law remains (it is collected only from land).

Ran (DH Bas): When we assess the father's intent, it is based on his land and Metaltelim. Even when we do not assess, we give a tenth of all property, including Metaltelim. There is no reason to give a tenth only of land, but to allow paying with money or land. Rather, the orphans owe a tenth of all his property, but they pay only from land. Why does the Rambam say that it is a tenth only of the land?!

Rosh: Rebbi taught that we collect food from Metaltelim, and all the more so we collect Parnasah from Metaltelim. That is letter of the law. Nowadays we collect from Metaltelim only due to an enactment. This is only for what was enacted. However, if a man married off a daughter in his lifetime and gave to her Metaltelim, we assess his intent and give to other girls from Metaltelim. 'Parnasah is collected only from land' does not mean that she gets only a tenth of the land. Rather, she gets a tenth of all the property. One normally gives a dowry according to (all) his wealth, i.e. land and Metaltelim. The debt is paid only from land, like the Kesuvah and food.

Tiferes Shmuel (2): I say that since Chachamim enacted the Shi'ur (of a tenth), even though it is not Tanai Kesuvah, and we see that Chachamim were stringent to collect it from sold property, without concern for buyers, all the more so Ge'onim enacted to collect from Metaltelim also for Parnasah, without concern for heirs. Tosfos (51a DH mi'Mekarka'i) says so.

Rambam (Hilchos Ishus 20:2): The tenth for a dowry is not a Tanai Kesuvah, so even after the Acharonim's enactment, it is collected only from land.

Magid Mishneh: It is a tenth only of the land. For Parnasah, we ignore Metaltelim. This is clear from Halachah 12. The Ramban and Rashba hold that when we assess the father's intent, it is based on his land and Metaltelim. This is like Rav in Kesuvos 50b. It seems that the Rambam agrees, for he distinguishes land from Metaltelim only regarding a tenth.

Rambam (ibid): It can be collected from rental of land. If the brothers wanted to give to her money in place of a tenth of the land, they may.

Magid Mishneh: The Rashba says that presumably, we collect from rental of land when the father rented it out and died before the rental was due. Since rental is due only at the end, it is like land, like the house itself. The father already acquired rental for the time that the tenant lived there, just it is not due until the end. This is why it says even rental.

Rambam (12): If an orphan girl's mother or brothers married her off and gave to her 100 Zuz, when she matures they must pay proper Parnasah, either our estimate of her father's intent, or a tenth of the land.

Nimukei Yosef (Bava Basra 35b DH Garsinan): Rental is like land when the father rented out land and died before it was due at the end of the year. It is like Peros that must remain attached to the land a while longer. If the heirs rented it out after the father died, this is Ra'uy (destined to be collected). Kesuvah and Parnasah are not collected from Ra'uy. If the father rented out land and payment was due before he died, this is like Metaltelim!

Tosfos (50b DH Mai): We estimate to give less than a tenth, but not more. Our estimate can help the girl only to collect from Metaltelim.

Poskim

Shulchan Aruch (EH 113:2): Parnasah is not a Tanai Kesuvah.

Chelkas Mechokek (1 and Beis Shmuel 5): Therefore, if a woman pardoned her Kesuvah, her daughter did not lose Parnasah, even according to the Rambam, who says that she lost food. Also, a man can command not to give it, for it is not his obligation. It is his sons' obligation, provided that their father was silent.

Shulchan Aruch (ibid): Therefore, even after the enactment of Rishonim and Acharonim, it is collected only from land.

Beis Yosef (DH u'Mah she'Chosav b'Shem): Sefer ha'Terumos and Tosfos (51a DH mi'Mekarka'i) say that nowadays even Parnasah is collected from Metaltelim. We can testify that a man wants to marry off his daughter from Metaltelim. This is like when we know a man's nature. Rava says that the Halachah follows R. Yehudah then (that we give based on our estimation). The Rif and Rambam say that Parnasah is only from land, but perhaps they merely gave the law according to the Gemara.

Rebuttal (Darchei Moshe 6): Since the Rif and Rambam did not distinguish like they distinguished other Tanai Kesuvah, this shows that they hold that it is not collected from Metaltelim even nowadays.

Chelkas Mechokek (7): They did not enact for Parnasah, therefore, there is no lien on the orphans' Metaltelim. The girls collect only from land, even though they are like creditors of the boys.

Shulchan Aruch (ibid): It can be collected even from rental of land (Rema - if the orphans did not yet collect it) and from what is Ra'uy.

Chelkas Mechokek (8): Obviously, it is collected from rental after the father died, for once he died there was a lien on all his land. Rather, even what was owed (for the time the tenant lived there, if payment was not due yet) is like Peros still need the land, which are like land. If the time (for payment) passed in the father's lifetime, the rent owed is not like land. The Rema means that it was not suitable to be collected yet.

Beis Shmuel (8): Once payment was due, the owed rental is Metaltelim. The Rema means that if they collected for the first part of the year, even though it was not due until the end, still it becomes Metaltelim. The Nimukei Yosef says that girls do not collect from what they rented out after he died, for it is Ra'uy. The Rosh and Mordechai say that they collect from Ra'uy. The Mordechai says that a creditor collects from Ra'uy. Chachamim were lenient about Kesuvah and food, but not for Parnasah. The Rosh holds that a creditor does not collect from Ra'uy. Parnasah is different, for the brothers owe her and they are alive. Maharam Lublin (15) says that the Rosh holds that a creditor collects from Ra'uy. This is astounding!

Chelkas Mechokek (9): If the father owed to her, she would not collect from Ra'uy, e.g. property that was later inherited from her father's father. Rather, her brothers owe her, therefore she collects from it. However, she gets only a tenth of what her father had when he died.

Shulchan Aruch (ibid): If the brothers wanted to give to her money in place of a tenth of the land, they may.

Rema: It is collected only from land, but when assessing the property to calculate a tenth, we assess also Metaltelim and collect a tenth from land. This is only when we give to her a tenth. When we assess the father's intent, we give according to our estimation from Metaltelim and from land. Some say that even when we assess his intent, we give only from land.

Gra (12): Kesuvos 50b shows that Metaltelim affect the amount given only when we assess the father's intent. One could say that Rava argues with Shmuel, but there no source for this (Ran).