Spotfire Ideas Portal
When making scatter plots, it is possible to enter a calculated column for the label. You can get quite creative with this, adding some text to go along with a numerical value on display.
Line charts, on the other hand, have no way to modify the labels. You should be able to have the exact same functionality as on scatter plots.
It's possible to make a scatter plot into a line chart by adding a LineBy, but I do not always like the way that scatter plot labels look in relation to line chart labels.