A holding rack (101, 201, 301, 401) has individual positions or compartments for dosage units (102, 102′, 202, 302). Each of the dosage units has a supply receptacle (104, 104′, 204, 304) and a dispensing head (103, 103′, 203, 303) that are connected to each other. The holding rack (101, 201, 301, 401) is equipped with a means for active user guidance (105, 105′, 210, 305) which, in a process of dispensing measured substance quantities from the different dosage units into a receiving container (411), directs the user in taking out and returning the different dosage units that are seated in the holding rack.