I have been looking around and saw that mercedes did have white square side indicators on the C class models round 1996 just before the modelchange in 1997. So, it is possible to get OEM white square shaped side indicators (although there is absolutely no difference between the mercedes side indicators and the in=pro side indicators).
These side indicators do not come on together with the parking lights. The correct euro name is side indicators (in the Netherlands/Germany) and repeaters (in the UK).
In Europe the turn signal lights do not come on with the city lights. We only have a 5Watt bulb in the headlight unit that is called city light and the indicators are used as turn signals only.
Thanks for the compliment, you are making me blush...
with a minor 600+k