[AccessD] Differentiating between different data groups within a sub-form

 Here is an interesting problem.
 
 How do you differentiate between different data
 groups within an MsAccews sub-form ?
 
 I would like to have sub-form which contains many
 room numbers.  Some are the same room number over
 and over while there will be other different room
 numbers.  The room numbers are sorted in ascending
 order.
  
 There will be a clump of 101's, followed by maybe
 a 102, followed by a group of 103's, etc., etc.
 
 I would like to draw a line between each clump, or
 change the background color for each clump.  
 
 Or any thing else - that would make it easer to
 see where one clump of room numbers change over
 to another clump of room numbers.
 
 Any ideas on how to do this ?
 
 Thanks.
 
 Sincerely,
 Edward Zuris
  <mailto:edzedz at comcast.net> edzedz at comcast.net