Reference for Kelim 24:13

שְׁלֹשָׁה סְדִינִין הֵן. הֶעָשׂוּי לִשְׁכִיבָה, טָמֵא מִדְרָס. לְוִילוֹן, טָמֵא טְמֵא מֵת. וְשֶׁל צוּרוֹת, טָהוֹר מִכְּלוּם:

There are three types of sheets: one made for lying upon is susceptible to <i>midras</i> impurity; [one made] to be a curtain is susceptible to corpse impurity; and one with designs is pure from all [types of impurities].

Jastrow