Data Marks/Data Tags are used to highlight points of interest on the graph. Data Marks can only be added during data collection and Data Tags can be made at any time. A Data Mark might be used to identify the time at which something occurs, e.g., crystals beginning to melt, or a light being turned on for photosynthesis. A Data Tag might be used to indicate where a particular event occurred such as when a ball reached the top of its flight.
In addition to the Mark/Tag itself, a helper object is also displayed, showing the X and Y values and optional text. A Data Mark has a black triangle in the upper right corner of the helper object, a Data Tag does not.
The appearance of the Mark/Tag on the graph follows the point protector settings for the y-axis column. This can be changed in the Column Options Dialog. To format the helper object, double-click it to bring up the Options dialog. Here, you can add text, edit what is displayed, and change the font settings. If the option Show on Graph is unchecked, the Mark/Tag will still be displayed, but the helper object will be hidden. To display the helper object again, choose Reveal Hidden Objects from Additional Object Options under the Options menu.
A Data Mark/Tag can be removed by clicking the X in the upper corner of the helper object.