A sort key that puts a node BETWEEN before and after within one point's segment.
before/after are the sort keys of the neighbours it lands between; either may be absent
(dropping at the head or the tail of a segment). The midpoint keeps every other node's key
untouched, which is what makes a move one write.
A sort key that puts a node BETWEEN
beforeandafterwithin one point's segment.before/afterare the sort keys of the neighbours it lands between; either may be absent (dropping at the head or the tail of a segment). The midpoint keeps every other node's key untouched, which is what makes a move one write.