book cover, satchel or bag
袠 centers on a container made of cloth: a book cover or a satchel/bag. Both meanings share the idea of wrapping or holding something in fabric.
袠 combines 衣 (clothing, cloth) with 失, which likely contributes a phonetic element. The character originally referred to a cloth wrapper or bag, later extended to book covers.
Picture a cloth garment (衣) that has lost (失) its shape and is now used as a bag or book cover. The cloth wraps around the contents like clothing.
For チツ, imagine a cloth bag holding a set of chits (small notes): chits -> チツ, and the bag keeps them covered like a book cover.
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