The world is full of ridiculous things. Consider StVZO. This abbreviation is mentioned in a lots of marketing materials (mostly from Asia). But no competent lawyer or legislator will refer to it because it's long time dead and the related requirements were moved to ISO 06742, etc. As for DIN 41773-1 ("Static power convertors; semiconductor rectifier equipment with IU-characteristics for charging of lead-acid batteries, guidelines"), one thing in common is that it's also not relevant now. But I'm not aware of the replacement. If no corresponding ENs were provided, why it's withdrawn?