Mishnah Berurah — משנה ברורה

Since they are not etc. - Behold, the Beit Yosef wrote that one can ask regarding our clothing that has two corners close to the neck and two corners close to the ground... why do we not affix ציצית to them? And he answered on this a few answers and the Darchei Moshe (ie. the Rem"a) rejected them and said his own reason for the custom [of not affixing ציצית to our clothing as described above], [namely] that since the mitzvah of ציצית is optimally to have two in front and two in back and our clothing has all four corners in front and it's impossible to wear them any other way, [therefore] they are not obligated in ציצית. And this is what he (i.e the Rem"a) [meant when he] said "since their corners are not fashioned in a manner etc.". And [regarding] the garment that's called "Rek", which has attached to it above, a piece of garment which is squared off and [folded over so that it's] resting on the shoulders from behind which is called "coll'nar" (ie. collar)... it is obvious that it is exempt because on the upper portion [of the "Rek"] there are no corners except for the corners of the collar which are resting slightly behind. And these are not corners since the two corners from behind are not aligned opposite the corners that are in front. Until here are the words of the Darchei Moshe. And the Magen Avraham wrote that since this ruling is weak in the hands of the Geonim (lit. Genius's) and they could not find the proper reason [because even on the reason of the Darchei Moshe one can cast doubt like the Pri Megadim wrote]. Therefore, one who is a "Yirei Shamayim" (G-d fearing person) should make one of the corners rounded, like the Beit Yosef wrote in the name of the "Zekeinim" (Elders). And this is the opinion of the Pri Megadim and other later halachic authorities. And especially in our times, regarding those new [types of] garments that are designed to be open from behind [this is the garment called "Kapotteh"], and is often found that the majority of it is open... according to the Darchei Moshe, it is obligated in ציצית since the two [corners] from behind are aligned opposite the two corners in front. Therefore, one who wants to exempt himself (so as not to enter into a questionable halachic situation) is required to make at least one of the four corners rounded, and then it is exempt from ציצית. And this is like what's written earlier in [Shulchan Aruch Siman 10] Se'if 9. And see further there in Biur Halacha. And even better would be to round off another two corners in order that it remains with only three, because now it has six. (this is referring to the Kapotteh which is like a long frock coat with a large slit in the back from the bottom-up (that takes up the majority). So there are four corners along the bottom - two in front and two in back. And then there are the two corners up top)