There is an additional line in both the target and actual plans that you can use to display availabilities.

Shifts or shift times indicated as availabilities are then displayed in this line.

You can use the Shift details dialog box to define the length of availabilities in both the shift plan and the day view, which allows you to define user-specific availability intervals.

The abbreviation used for the availability is then highlighted in the shift plan.
This indicates that the availability interval has been changed.

You can choose to hide or show the line used for availabilities.