An ascorbic acid derivative of the formula Ia: where the variables independently of one another have the following meanings:R1 and R2 independently of one another are hydrogen or C1-C20-acyl;R3 is hydrogen or a cation selected from the group consisting of NH4+, alkali metal and alkaline earth metal cations;R4 is C1-C6-alkoxycarbonyl,and a process for its preparation. Messages left for a user are deposited in folders maintained by the messaging services. A database collects one or more patient care records by organizing one or more patient care records with a plurality of the collected measures sets and storing the collected measures set into a patient care record for the individual patient. The computing platform system moderates the generated data by securing sensitive information of the generated data from access by the computing platform system, and providing operational information from the generated data. Failure of the position sensors andor the control lines that are allocated to said sensors can be detected. The cross section of the core of the coil andor of the magnetically conductive connecting elements is as small as possible.