Translation:Shulchan Aruch/Orach Chaim/282
1. We bring out a Torah scroll and seven read from it. And if one wants to add [to the number of readings], one adds. RAMA: And this is the law: on a Festival, it is permitted to add to the count of readers (Rambam, The Laws of Prayer and Repentence, chapter 12; Maharam; and Beit Yosef). And there are those who say that on a Festival one may not add (Ran, chapter "Ha-Korei"). And thus (i.e. the latter) they practiced in these countries (i.e. Ashkenaz), except for on Simchat Torah when we add many. Also on every Festival, the Maftir is not [included in] the count of readers, as seen below.
2. It is permitted to read [the same readings for] those who are called up to the Torah multiple times, even though this one read what this [other] one has [already] read and goes back and makes a blessing - there is nothing [problematic] with this. RAMA: And there are some who forbid [this] (Mordekhai, Sof Megillah) And this is our custom in these countries (i.e. Ashkenaz) except for on Simchat Torah they practiced to multiply the readers and practiced according to the first opinion.
3. All count towards the seven who are called up, even a woman and a child who knows who we bless, but the Sages said: A woman shall not read [the Torah] in public, out of concern for the honor of the community. RAMA: And these specifically may be include in those who read, but they may not be all women or children (who are listening) (Ra"n and Riva"sh). And a Canaanite slave is treated as a woman, but if his mother is Jewish he may go up [to read the Torah] (Hagahot Maimoniyot, Prayer and the Priestly Blessing, ch. 12). And it is prohibited to read with one's head uncovered. And there is no prohibition to call up a respected ignoramus, who is rich and powerful, before learned men; for it is not disrespectful to the learned men, rather an honor to the Torah which is honored by great men (Ohr Zaru'a). And a mamzer may go up to [read from] the Torah (Mahar"a of Prague). And see above, Siman 136, for the order of those who are called up.
4. It is customary to read 7 (aliyot) to complete the parshah. We then say Kaddish, and then go back and the maftir reads what the seventh person read. RAMA: It is our custom on Yom Tov that the maftir is not from the amount of the readers. However, during the week, when it is forbidden to add to the amount of readers, the third one is the maftir. On a day where two or three Torahs are taken out, the maftir reads the last one and a minor may read the additional parshah, or from the four parshiyot that are added in Adar, and this is our custom (R"an; Mordechai). Even though there are those who disagree, and say kaddish prior to the maftir being called up, there is no difference in this regarding adding to the amount of (aliyos) or not, or regarding taking out two or three Torahs (Beis Yosef in the name of R' Yeshayah; the Rosh; R' Yerucham).
5. If there is no one else in a synagogue who knows how to read the Haftarah from the works of the Prophets aside from one of those who already received an aliyah, [he may be called again as maftir]. When the sheliach tzibbur had already recited Kaddish after the [required] number [of aliyos] were completed, he who wants to do maftir must go back and read and make a blessing before and after the reading. RAMA: However, if he did not yet say kaddish, one of the original seven may do maftir if he knows how. And if there are others who know how to do the maftir, then one who previously had an aliyah should not do it. (Or Zarua). See above Siman 144.
6. If the sheliach tzibbur erred and completed the [weekly] Torah reading with the sixth aliyah and recited Kaddish it is not necessary to call a seventh person to the Torah in addition to the maftir. Instead, [the sheliach tzibbur] should read [some of what] he read for the sixth aliyah for the maftir. This is sufficient, since fundamentally, [the halachah follows the opinion that] the maftir may be counted among the seven [required aliyos].
7. We read the parshah in the morning prayer on Shabbat. If the sheliach tzibbur skipped even one word, and indeed, even one letter in the Shabbos morning Torah reading, he must go back and read the verse [in which] he skipped [the word or letter] together with two verses that are next to it, reciting a blessing beforehand and afterwards. If the person who received that aliyah already recited the blessing after the Torah reading – indeed, even if [the congregation] already concluded the Torah reading, and the Haftarah and the Mussaf Service were recited – the sheliach tzibbur or another person must go back, recite the three verses that include the skipped [word or letter] in this congregation together with a blessing beforehand and afterwards.