Everyone remembers the box and the cartridge. The paper is what gets lost — thrown out, worn away, separated from the game — and that is exactly why it carries so much of a complete copy's value. Manuals and inserts are a completeness requirement, a condition variable, and a print-window fingerprint all at once, which makes reading them a core collector skill.
A truly complete box holds more than a manual. The set can include the registration or warranty card, poster maps, control-overlay inserts, dust sleeves, the poly bag the manual shipped in, ad flyers, and — for some titles — feelies and premiums unique to the release. The market knows the exact set for anchor titles, and 'complete' means all of it, not most of it.
Manuals carry revision codes and paper-stock changes; inserts appear, change, and disappear across print runs. A first-print box married to a first-print manual is worth more than a first-print box with a later manual, because the market rewards internal consistency. Verifying the paper matches the box is how a completist confirms a copy is a coherent first print rather than a marriage of parts.
Because the paper is the hardest part to keep, the gap between complete and near-complete is priced steeply — a missing insert routinely takes a CIB copy to 40–60% of full value. This is the completist's edge: the knowledge of exactly what belongs in a box lets you spot the incomplete copy sold as complete, and the complete copy underpriced by a seller who didn't know what they had.