Might be a silly question but.... what does SNd3 mean?

I have small silver condiment spoon with a glass pot and it has the letters S N d 3 stamped in individual boxes… I have googled and found other items with this mark but none of the descriptions explain the hallmark… could be a really rookie thing to ask but if anyone can shed some light I would be grateful! :question:

Very sorry about the lack of a picture but my digital camera had a watery accident and isn’t functional… however the stamp is just letters and now images and is in the capital and lowercase as listed in my question…

It took a little while, but it suddenly dawned on me… It’s EPNS upside down!

EPNS - electroplated nickel silver.