Re-Zoning triplex from business to residential

[Lois Stern]

I'm looking at a property - a Townhouse in a mixed use neighborhood.  Somewhere along the way, an owner decided to get the TH zoned for business use only and is now selling it and stating on the sales sheet that it could be turned into 3-4 apartments.

Does anyone know if this is a simple process of licensing or is there more to it?  We are in Baltimore MD, by the way.