I am just starting to wade into the murky waters of the renfe site for the first time. I am looking at tickets for a family of four Barcelona to Madrid. Currently I am at the screen where I choose a fare with several little icons next to them (M, P, P+ and F). I think I have figured out that "P" stands for promo and P+ stands for Promo plus fares, but what do the others mean? The children will be 4 and 6 at the time of travel, is is better to book at these rates than trying to figure out how to get a child ticket? Any advice at all you have for this Spain newbie would be much appreciated!