What are the correct terms for these visualization components?

What is the proper term for a vertical line on a visualization that follows a mouse cursor?

_{Nb, screenshots have removed my mouse cursor but it exists on the same vertical plane as the dot in the second figure in both visualizations.}

What is the name of a point on a visualization that follows a mouse cursor?

Both are supplementary mouse cursors, but do they have a canonical name?

^{Please tell me if these questions should be split into two or better suited for a different SE site.}