KEYSTONE
Yes I know that THE keystone is known (POTUS/MI), but things have double meanings.
I thought this was already a working theory here, but doesn't each Stringer serve as / indicate the keystone for a specific crumb? All the pieces on the map, stringer IDs which piece is the keystone for this crumb, other numbers/sequences in the crumb indicate which other pieces/actors are included in the crumb narrative.