I have just been editing all route relations for rcn routes in Belgium. My use of the forward and backward roles is as follows:
On the left side of way A, there is a node with a lower rcn_ref On the right side of way F there is a node with a higher rcn_ref
So following all empty roles + all forward roles should get one from the lower rcn_ref to the higher rcn_ref.
And following all empty roles + all backward roles (reversed) should get one from the higher rcn_ref to the lower rcn_ref.
This allows for automated check of continuity of a route in the forward and backward directions. I wrote a Python script which can be run regularly to validate that the routes remain continuous. This is for quality control, to be able to detect when contributors break the relations while editing.
- This is not the accepted usage of forward/backward roles. Forward/backward is defined as your direction of travel with respect to the direction of the way in OSM. I understand that your scheme might be easier for your script, but forward/backward would mean something different to other users. --Ldp 11:53, 28 September 2011 (BST)
- I'll have to come up with a way to change them to comply to that then and especially a way to decide what to do when there is a fork and how to determine which is the forward and backward direction, the way I understand it.