As best I can tell, the Dodge Brothers company introduced the Business Coupe in 1922 - 23. I believe the 'Brothers' part of the name was dropped when the Chrysler Corporation bought the company in 1928. I know they continued to build Business Coupes into the 1950's but they were badged with the name Dodge only.
So you tag is from 1922 - 28. I looked at pics of several early 20's DB Business Coupes and I did not see a similar tag on any of them. I suppose it could have been attached to the frame and was simply not visible in the pictures.