What does " footlong" means?
The nutritional information provided at Subway includes values for sandwiches made with 9-grain wheat bread, lettuce, tomatoes, onions, green peppers and cucumbers. There is no added cheese, mayonnaise, avocado or extra meat. In addition, all calorie counts are for 6" sandwiches. If you buy a footlong Subway, you need to double the values.
my question is : What does " footlong" means?