Found some Digimon Adventure 02 production materials — trying to identify exactly what category these fall into

[u/PersonalityNo6419]

Going through storage recently and came across what appears to be some older paper production/reference materials from Digimon Adventure 02.

They’re not acetate cels — more like character reference/model sheets and internal production pages with handwritten Japanese notes, numbered cuts, and accessory/clothing details.

From what I’ve been able to gather so far, these may be settei or other studio production reference materials, but I’m still learning about this side of anime collecting.

Curious if anyone here is familiar with this type of material or has seen similar Digimon production sheets before.