We'll first talk about Tumah (ritual impurity) called Tum'at Midras, when a Zav (a man with a discharge), a Zava (a woman with a discharge), a Nida (a menstruating woman), or a Yoledet, the woman who gave birth, put their weight onto an object, even though they're not actually touching the object itself, but are on something that is on the object. For example, let's say they're on a pillow that is on a chair. Then it becomes Tameh (ritually impure); that chair becomes Tameh, even if the Tameh person didn't touch it directly. But this Tumah is transmitted only when the item in question is made to support a person, like a chair or a pillow. If it wasn't made to support a person, then it's not subject to Tum'at Midras. We'll talk about a certain type of mat and whether it was subject to this type of Tumah or not. The Mishnah says, “Kol hachotzalot teme'ot tamei met,” All different types of reed mats can become Tameh from a corpse, from a dead body, but they cannot become Tameh through Tum'at Midras, because they're not usually made for lying or sitting down on. So reed mats cannot become Tameh through Tum'at Midras. “Divrei Rabbi Dosa,” this is the opinion of Rabbi Dosa. “VehaChachamim (the Sages) omrim Midras,” VehaChachamim say they can become Tameh as well, from Midras, because sometimes people do lie down on them or have them designated for that very purpose.
The next Machloket (disagreement) we'll have is about an item made of threads that were then braided together. When the Torah talks about things that can become Tameh, it mentions the word sak. Sak is something that's a woven piece of cloth. So we'll have a Machloket about whether this excludes items that were made through braiding. In other words, braiding is a type of weaving. All different braided items are considered to be Tahor (ritually pure). They cannot become Tameh except for belts. “Divrei Rabbi Dosa”: Rabbi Dosa says the Torah specifies only a woven item to become Tameh, and therefore excludes braided ones. But a belt can become Tameh, even though it may be braided, because a belt is not considered to be just like a regular article of clothing; it's considered to be a Tachshit, an ornament. And an ornament can become Tameh regardless of how it was made, so therefore a woven belt can become Tameh. All braided items, all of them, can become Tameh except for those braided ropes of wool dealers. The Chachamim are basically saying that braided items are the same as a woven item, because the process of braiding them is very similar to that of weaving. Weaving and braiding are almost one and the same, so therefore they can become Tameh. But a wool dealer's rope cannot become Tameh because it's woven in such a loose fashion; therefore, it's not considered to be similar at all to the woven style. So, the braided items, the seller of wool is not considered to be at all similar to the woven, so therefore it cannot become Tameh.