Description. Unarticulated and tacit. People act on it but cannot put it into words, so it is never written and leaves no trace.
Example. Grandfather reads the farm with his boots. He knows the low field by the river floods if the rain comes early, that the top paddock dries first, that the soil is ready when it crumbles a certain way in his hand. Ask him how and he shrugs. Forty years on the same ground put it in his legs, not on paper.
Cost.It walks out the door the day they leave.