Creating stand-by duties requires a little preparation such as setting up a stand-by subject and specifying which teachers are to hold how many stand-by periods.
Entering this data has been made easier since a dialogue opens the first time the stand-by window is opened allowing you to input the required data.

You can specify the following parameters for the stand-by subject in this window:
Short name, full name, maximum stand-by periods and teachers who are to take stand-by periods.
The stand-by window then opens and you can enter the number of stand-by periods for the periods in question.