Assertion: chord's key | /r/AtLocation | the center of a key
Facets:
value: at the joining of three keys
type: TEMPORAL
value: across the boundary of two keys
type: LOCATION
Source sentences:
text: One solution used a grid of hexagonal keys with symbols inscribed into dimples in the keys that were either in the center of a key, across the boundary of two keys, or at the joining of three keys.