Knowledge gap
A knowledge gap is a piece of knowledge that critical work depends on but that the organisation has never recorded, verified, or assigned an owner to.
The most expensive gaps are not missing documents. They are undocumented criteria: the threshold that decides when an exception is allowed, the reason a system was built one way, the condition under which a rule does not apply.
Enterprise search cannot surface a gap, because there is no document to return. Absence has to be inferred from the work itself: a decision that keeps getting escalated to the same person, a policy with no bound owner, two sources that disagree.
A gap is not a failure or a fault. Most gaps are simply unknowns, which is why treating them as alerts makes a coverage map read as an indictment of the team that owns it.