scatter graphs with multiple series require 1 tooltip column per series

[KPax23]

I noticed an odd behavior with tooltips in multiseries scatter graphs.
It appears that one needs to add a tooltip column to the data for each
series' y column instead of just a single tooltip column for all
series y columns.
This is somewhat confusing to me since, if I understand correctly,
each row of scatter graph data may only contain one single non-null
value across all y columns. If that is the case then a single tooltip
column should really suffice since the tooltip value could not be
associated with more than one scatter graph dot.
Is this by design or a bug? Could it be improved to where having a
single tooltip column for all y columns in scatter graph data would
work?

Thanks
K

[asgallant]

Nothing prevents you from having multiple values in a given row: http://jsfiddle.net/ebyfc/