OptionalinstanceIndicator instance id, when kind is 'indicator'.
OptionalscaleWhich of the pane's scales that strip acts on, when kind is
'price-scale': the side's own scale, or the hidden overlay scale ('') when
the side carries no series of its own and the pane's values are all on the
overlay. It is the argument the priceAxis* calls take.
OptionalseriesSeries type, when kind is 'series'.
OptionalsideWhich axis strip was hit, when kind is 'price-scale'.
Hit-test id of the thing under the pointer, when there was one.