This patch modifies the turn heading adjustment code so that the GPS will tell you to turn when you are routing from a main road to a side road in situations like this: S S ^ S | MMMMMMMMMMMMMM | M | M | M M You can see that the main road goes around a left corner and the side road carries straight on. Without this patch, neither mapsource or a Nuvi will tell you to turn right at this junction even if the side road has a different road class/speed from the main road. This patch also allows you to globally enable/disable the possible adjustments by providing a bitmask with the --adjust-turn-headings option. By default, all (currently, there are 2) kinds of adjustments are enabled. See the help blurb for more info. A value of 1 gives the old behaviour. Mark