On Tue, Mar 23, 2010 at 8:13 AM, Ugo Cupcic wrote: > Ok, thanks for your answers. I'm now using a type flag in my message, > but I wanted to be sure I was doing it properly. hi Ugo, Rather than use a flag in a message to switch between types, you should consider defining multiple message types. We designed ROS to make it easy to define new messages, and to hook up multiple publishers and subscribers. You're free to use a flag, of course; it's just not the recommended design pattern. brian.