Specifies how the last grouped point is positioned on the xAxis. If firstAnchor and/or lastAnchor are defined, then those options take precedence over anchor for the first and/or last grouped points. Available options:
-start places the point at the beginning of the group
(e.g. range 00:00:00 - 23:59:59 -> 00:00:00)
-middle places the point in the middle of the group
(e.g. range 00:00:00 - 23:59:59 -> 12:00:00)
-end places the point at the end of the group
(e.g. range 00:00:00 - 23:59:59 -> 23:59:59)
-firstPoint the first point in the group
(e.g. points at 00:13, 00:35, 00:59 -> 00:13)
-lastPoint the last point in the group
(e.g. points at 00:13, 00:35, 00:59 -> 00:59)