What do these markings mean?

I have inherited sterling silver centerpiece I can see that it is sterling and made by Bailey, Banks and Biddle but I don’t know what the rest of the marks/numbers mean. Can you help? Thanks!!
Silver marks 1 crop.jpg
Silver Marks 2 crop.jpg

1019X is most likely a pattern number or some other form of internal factory ID.

Thank you! Does anyone know what the keystone with an S in it is?

I don’t know what significance it might have but it seems to be part of BB&B’s trade mark.