Correct direction of line for guardrails and retaining walls

I notice that when I draw guardrails and retaining walls in the iD editor, I get triangular arrows sown perpendicular to the line, which depend on the direction of the line. In the case of a guardrail, should these arrows point toward or away from the road? In the case of a retaining wall, should these arrows point up-hill or down-hill?


Quoted from :-

If there is a clear inner/outer demarcation to the guard rail, construct the line so that the right side is inner and left side is outer.

The page pertaing to retaining walls is here :-
“Lower side on right side of way direction.”

Okay, thank you. I fully understand retaining wall direction now, but I am still not completely clear what inner and outer means with respect to a guardrail. Say for example, you have a guardrail between a road and a ditch, preventing a car from slipping into the ditch. Would the right/inner side of the guardrail be the road side or the ditch side?

My understanding so far was that the right/“inner” side should be the road side, but the more I think about this, the more ambiguous the wording in the documentation seems to me…