Sheets are used in the production of scrolls and quires. Sheet can be made from either paper or parchment. They are stored under Sheet (top stockpile category).
For more information see: paper industry.
Paper is made from cloth plants mashed into slurry (at a quern/millstone) and then pressed on a screw press.
Both of these actions use the papermaking labor.
Papyrus sheets are made directly from the papyrus plant at a farmer's workshop.
Parchment is made from hide and milk of lime at a tanner's shop. Parchment made from the hide of a cow is called vellum.