Mishnah Berurah — משנה ברורה

To a public domain - And to [wear invalid ציצית on Shabbos in] a karmelit (an area that is not a private domain and not a public domain, but conceptually somewhere in between) is forbidden on a rabbinic level. And the same applies to all other invalidations. For example: if the majority of the garment was closed up, or if the ציצית were made/affixed not in the right place - [such as] higher than three finger-widths [from the edge of the garment], or lower than [length of the] thumb from the knuckle to the tip [from the edge of the garment], and all similar cases - or if the four corners (ie. the length and width of the garment itself) was less than the measurement described in siman 16, see there. In all those [cases], it is forbidden to go out [while wearing] them [on Shabbos], even to a karmelit on a rabbinic level. And [regarding] a garment which is open exactly halfway (ie. a tallit katan where the sides under the arms were stitched up so that it was exactly half-open and half-closed (if measured from the top, by the shoulder, to the bottom)), see above in Siman 10 in Mishnah Berurah se'if katan 27.