[OSM-newbies] adding POI in Potlatch that is not on the menu

[John F. Eldredge]

When editing in Potlatch, how do you go about adding a POI that is not 
in the list of default POI types?  The building in which I work used to 
be a hospital.  Several years ago, it ceased to be a hospital, and was 
converted into commercial office space.  However, it still shows up on 
the slippy map at OpenStreetMap.org as "Donelson Hospital".  I would 
like to correct this, and have it show whatever the correct POI icon is 
for business offices, as well as having a note saying "former Donelson 
Hospital".  The list of POI icons at the bottom of the Potlatch screen 
does not show an "office" type.  Is there a POI type defined for 
offices, or do I need to trace the building as an area, then set the 
properties of the area?