Caldav command from item value possible?

Instead of
BEGIN:FF_BD_SOLL_Temperatur:22
i would like to use
BEGIN:FF_BD_SOLL_Temperatur:v_FF_BD_SOLL_TEMP_DAY
Is something like that possible in an caldav event?

v_FF_BD_SOLL_TEMP_DAY is a virtual item wich i use in sitemap with a setpoint