Hello @Paul_Felshaw
Business Details > Geomodifier is field which is automatically included for location entities, and it syncs out to Listings facility for publishing your locations listings. N.B. Not every publisher supports the Geomodifier field.
Since “Geomodifiers” can be used uniquely for each location, and are often the city, region, shopping center, mall, or a different location descriptor, you can use like you are planning to use it. However, if there is specific expectation that you are willing to achieve, please share it so that the approach can be confirmed accordingly.
Hope it helps.