Modify "Business Description" listing field
				
				
                
                    
                    
                
                
                    
						
                
                
                    This question may belong in another forum, I am not yet savy about the protocol.  I wish to offer free listings and paid listings whose benefit is additional specialzed fields offered through custom fields in a group to enhance the information presented by the listing.  Some potential listers in  my area may be able to use the standard "business description" field to meet all of their needs.  I want to modify the field in some way to limit the amount of information it can hold. I am technical and have other wordpress sites that I have made fairly externsive modifications to the code, but I don't know where to go to modify the characteristics of a data field.
Any suggestions are welcome.
Thanks