TOOLTIP, as in any other places in on your PC, is responsible to show short info about the column when you hover your mouse over the column header. It’s very useful when you have a lots of fields in you grid and you’re optimizing the width of the column by minimizing the description of the column itself. It is common behaviour for example for checkboxes or for icon columns. In this case the Tooltip is very helpful for explaining the user the meaning of the column.
Figure 81 ZDEMO_AIN_CL34 Tooltip of an column
Additionally if you’ll not use SELTEXT field, then the value from TOOLTIP will be used as description used to describe the column in the change layout screen.
Figure 82 ZDEMO_AIN_CL34 ABAP Code for Tooltip
Figure 83 ZDEMO_AIN_CL34 Change layout screen